This is work in progress. I'll be adding more info soon.
Since a lot of people still report problems with this fight this should be useful. Seeing how many classes can actually solo it, building a party that would faceroll the fight is not a big issue, even without using the so called "cheese"
Out of scientific interest raised from discussions with Kaylon I've decided to give it a try and beat Adra dragon solo with all classes, with a few self restrictions:
No intentional AI abuse
No petrify traps or spells (although they are far from being as OP as they were in 1.04 and in fact there are easier ways to beat the fight with many classes now)
Fight the dragon and ads simultaneously - there are ways to glitch the fight so that dragon does not aggro immediately and you can eliminate them separately. Kiting is ok though.
(Optional) no hard CC effects. Debuffs are ok. I'll analyse both hard CC and no hard CC approaches.
(Optional) minimize consumable usage. Majority of the classes can not do it without consumables at all, but I try to use as few as possible
This turned out to be a quite interesting experience which allowed me to learn a bit more about game mechanics and the boundaries that can be pushed. This guide will examine the strategies to do this fight solo, but they are applicable in a party as well obviously and many of them will work against other tough opponents in the game, so it's not only about the dragon really.
Classes done so far (by me personally, maybe someone else did some of the missing classes as well):
Wizard Priest Druid Cipher Paladin (based on Kaylon's strategy, I wanted to test some variations, but ultimately didn't find a way to do enough damage without stocking up on scrolls) Fighter
I'll try the other classes as well, monk is probably doable in a similar fashion to paladin and fighter, others seem more tricky to figure out.
So what's this fight, like many other PoE fights is about? Right, accuracy and defenses. Basically you want to either:
Lockdown enemies so that they are unable to harm you while you harm them. This can be achieved via hard CC, debuffs and just keeping distance
Make yourself impervious to enemy attacks
Ideally, both. You also need to deal damage somehow.
Let's take a look at the dragon's stats. The most important ones are saves and accuracy, DT is interesting too, but a bit less so.
Acc: 108. Since it's a level 12 creature all abilities get +12 accuracy bonus, so effective accuracy is 120. This means you need 170 to only risk grazed and 205 for full immunity in a relevant defense attribute. Dragon attacks target reflex, deflection and fortitude. No damaging attack targets will, but dragon's fear aura which reduces accuracy by 20 targets it. Long range attacks only target reflex (!).
Defenses: Def 133, Fort 136, Ref 112, Will 116 - As seen fort and defl are very problematic to target. best bet is to start from reflex or will attacks.
DR 28, Slash 21, Burn 35, Freeze 21, Shock 42 - You want to prioritize slash and freeze damage and avoid shock and burn (but not really, we'll see why later )
Other notable properties:
The dragon is VERY slow. Thus, any movement debuffs make her effectively stuck.
Basic info on afflictions and stacking:
Afflictions stack just like any other magic bonus in the game. E.g. If blinded reduces reflex by 20 and hobbled reduces reflex by 20, only 1 of the bonuses will apply (a larger one, or random if equal). However, this applies to all affliction penalties separately, thus blind accuracy penalty will work unless overridden by some other accuracy penalty.
General notes that apply to all strategies:
You really don't want to fight the dragon with -20 accuracy from the aura. All classes can counter it with protection vs fear scroll. Alternatively, paladins have righteous soul and priests have the spell itself.
You want to buff your accuracy as much as possible. Generally usable stuff includes gauntlets of accuracy (random loot), eldrich aim potions/war paint potions/valor scrolls. Other stuff is mostly class specific.
General notations:
(reflex) -> (will) denotes a spell/ability that targets reflex and debuffs will. Naturally, for adra dragon we want spells that target reflex/will and debuff smth else or further debuff these stats.
(acc++) denotes a spell with much higher accuracy than normal. Generally these are either trap or wall spells.
Let's take a look at what different classes can do in terms of debuffs.
Druid
Druid doesn't have many strong buffs and suffers from the fact that the majority of his CC/debuff spells target fortitude. However, the situation is not unsalvageable. Let's look at the spells:
CC/Debuffs
Level 1
Nature's mark: (will) -> (reflex, deflection). Not exactly terrible for a first level spell, but -10 is not much and fortitude is really the save we want to debuff
Charm beast: (will) -> (all, disable). Fun thing, dragon is a beast. Charm provides a beastly (pun intended) defuff on all devenses that will stack with individual defense debuffs. The downside is, you won't be able to use foe only spells vs a charmed target. The upside is that dragon might just wipe out her minions while charmed.
Sunbeam: (reflex) -> (reflex, deflection, accuracy, speed). Blind is one of the best effects to land on the dragon, since it reduces movement speed to almost nonexistent, while reducing both defenses and offensive potential. And sunbeam targets the weakest save. Recommended.
Vile thorns: (fortitude) -> (fortitude, will). Sickened is an OK debuff, however it gets almost completely overridden by the stronger Weakened, apart from -1 to some stats. Targeting fortitude and close range do not help this spell at all.
Level 2:
Previously blizzard was a strong debuff on this level, but in 1.05 it has been nerfed to be completely worthless (balance in action). This level has other solid spells however. As for CC:
Hold beasts: (will) -> (reflex+++, deflection, disable) - basically this is beast only improved mental binding. Paralysis ruins reflex, so if you land it you can unleash all your reflex spells without a second thought.
Level 3:
Returning storm: (fortitude) -> (reflex, deflection, disable). Damage portion is vs reflex, but stun is vs fortitude. Long casting time makes this spell not that useful for this particular fight, plus fort is not the defense you'd like to attack first.
Stag's horn: (deflection) -> (deflection, reflex). This has been nerfed for no good reason as well. Debuff was inferior to blind, and now is even worse, plus it targets deflection, which you don't really want to target.
Spreading Plague: (fortitude) -> (will, reflex, fortitude, speed). This is a very strong debuff that reduces all saves, however it needs to beat fortitude first, which is high for many strong mobs including the dragon. The "no save" rotfinger gloves version makes things much easier, but we aren't counting on it here since it's kinda cheesy.
Level 4:
Calling the world's maw: (fortitude) -> (reflex, deflection, disable). Hard CC with affliction that slightly reduces defenses and good duration. Good spell, but not for this fight.
Overwhelming wave: (fortitude) -> (reflex, deflection, disable). Similar to the previous spell, but more powerful. Still not what we want.
Wicked briars: (fortitude) -> (reflex, speed) - On the first look, this is not a debuff we want. However, it's a cloud spell, meaning many chances to apply the debuff. So once we deal with target's fort, it becomes a great stalling mechanism (since it debuffs speed)
Level 5:
Embrace the Earth Talon - (fortitude) -> (reflex+++, deflection, damage+++, disable). Infamous petrify. Actually the wrong tooltip on the spell lead to misconception that it targets reflex. The damage part does, but petrify is vs fortitude. This explains these times when the spell dealt damage but petrify did not trigger for me. I've been confused about it for a long time. It's a decent option if you manage to land it for full duration despite all the fortitude, however there are better options now that petrify is x2 only.
Nature's terror - (will) -> (will, reflex, accuracy). This is a decent option for close combat, and since it's and aura, it gets many chances to hit, but you don't want to approach the dragon that close
Plague of insects: (fortitude) -> (fortitude, will). Again, not the debuff pattern we want. However, this spell is awesome, just not as a debuff.
Relentless storm: (fortitude) -> (reflex, deflection, disable). Again not what we want in terms of defense, however this spell hits many times repeatedly giving many chances to apply and is excellent against the ads. Once the fortitude is reduced it stuns the dragon fairly well too.
Wall of thorns: (acc++)(fortitude) -> (fortitude, will, speed) Finally, this is what we want! Wall spells hit extremely often and have increased accuracy compared to normal spells. Even though it attacks fort, it's absolutely guaranteed to weaken the dragon crossing it, opening easier will and fort attacks.
Level 6:
Venombloom (fortitude) -> (will, fortitude, accuracy, minor reflex, speed). Even though it targets fortitude, once you manage to weaken the dragon it does a good job at generating additional hits to reapply the debuff, plus it deals solid raw damage.
So, based on this we can conceive the following debuff strategy:
Run to a chokepoint and use wall of thorns. Optionally overlap with wicked briars (will have much better chance to hit once the wall applies its debuff)
(if using hard CCs) - Now it's much easier to land charm/hold beasts, since will is significantly lowered, further reducing defenses and locking down the dragon
Alternatively proceed with sunbeam. In combination with wicked briars it will be able to beat the reflex save one way or another (you only need a graze) and lower movespeed to negligible level
Proceed with damaging stuff
Damage
Now, some notes on damage. In practice, the best damaging spells vs tough targets are DoTs. DoT spells are mitigated by only a fraction of target's DT (even though it is applied multiple times), plus they scale from both might and intellect, giving very high total damage over duration. Raw DoTs are obviously even better.
Thus, the best damaging druid spells really are:
Autumn's decay - Solid corrode damage, 100+ corrode DoT over duration with maxed might and int (including resting bonuses). Target's reflex, which is also good for us.
Insect swarm - another solid DoT. Worse than decay, since it targets fortitude, but since we can't stack same DoTs this will do.
Plague of insects - now this one also targets fort and is a bit slow, however it's raw damage, huge aoe and range. This will easily wipe all the ads while severely damaging the dragon over (quite a long period of) time.
Venombloom - Essentially another fort targeting DoT type spell, since it's a cloud it's not reliant on a single hit or miss, but requires you to keep the targets stationary
So what do we do once we establish a chokepoint with Briars/Walls of Thorns? Right, we spam Venomblooms, and throw a plague of insects on top. This usually would be sufficient to whittle down both the dragon and the ads quite fast. If anything gets through, Relentless Storm is an excelent countermeasure to lockdown and finish anything foolish enough to approach.
This approach allows the Druid to solo the fight. Obviously, with accuracy buffs from other party members like priests it would be even easier. i'll be posting on party synergies later.
Finally some math.
Level 12 druid spell accuracy: 53 (base) + 12 (leve) + 10 (spell modifier) + 5 (if wood elf) = 75-80. Let's assume wood elf (80) from here.
Weakened debuff: -20 will, fort, -2 might, -2 con = -20 will, -28 fort.
Dragon's fort = 136 - 28 (weakened) = 106.
One talent I forgot to mention: Scale-breaker - obtainable by not attacking the dragon immediately and doing its quest. -12 to all saves, accuracy, -6 DT, no save.
So 106 - 12 = 94.
finally if druid is main he can have mob justice from siding with the dozens and you can use figurines (imo ivory wurn is best for this as you can keep it out of harm's way) to "mark" the dragon. Druid's accuracy = 85.
Also, if you manage to find gauntlets of accuracy you can push it to 90.
Finally, accuracy buff from scroll of valor/potions pushes it to 105. Let's assume 100-105 range.
Vs dragon's fort (weakened, scale-breaker): 4-9% miss, 35% graze, 50% hit, 4-11% crit. Hits not 100% guaranteed but very likely.
If we charm the dragon.
136 - 28 (weakened) - (25 charmed) = 81. 0% miss 26-31% graze 50% hit 19-24% crit. No misses, but we can't use foe only spells
In both cases, spells that roll multiple times like Wicked Briars are all but guaranteed to hit.
Reflex:
112 (base) - (24 hobbled) = 88. 0-3% miss etc.
-12 (scalebreaker) = 76. 0% miss.
Blind also applies reflex debuff, that doesn't stack, however it's -4 perception debuff stacks with hobbled -2 dex, so if target is both hobbled and blind this is is -32 reflex.
Hold beasts pretty much annuls the reflex.
Will:
116 (base) - 20 (weakened) = 96. 6-11% miss.
-12 (scalebreaker) = 84. 0% miss.
Buffed up wall of thorns accuracy: 144 (not sure how this one is calculated), ticks every second.
TL;DR Druid summary
Maximise your accuracy. Counter fear aura with prayer against fear, use scroll of valor/warpaint/eldrich aim (one of)
Maximise your INT for debuff/CC duration and DoT damage via food/rest bonuses/items first
Maximise might next for even more damage
Establish a chokepoint
Use wall of thorns for guaranteed weaken and overlapping wicked briars for high chance hobble
Use scale-breaker
Use blind/paralyse/charm (subeam/hold/charm bests) next
Proceed with clouds and DoTs to wipe the opposition (Plague of insects, insect swarm, autumn's decay, venombloom)
Don't try to tank, druid is not well suited for this.
Priest
Priest has great buffs, debuffs, CC and damage. He also has great accuracy, since some of his spells have a +15 modifier and he has good accuracy buffs on top. This is probably the class that can do it with no consumables at all, but I'd still recommend using some just to be sure. We were not analyzing tanking stats and strategies before, but we will with a priest, since priest can do it if needed. If I were to list the weaknesses of the priest class, they would probably be: slow casting and relatively short buff duration, compared to wizard anyway. Both of these can be mitigated however.
CC/Debuffs
Level 1:
Barbs of condemnation - (fort) -> (all) Not that bad for a level 1 spell, but the debuff is not that great and it attacks fort, which is generally bad
Divine Terror: (will) -> (will, reflex, accuracy) Attacking will is ok, but debuffs are quite weak
Halt - (will) -> (reflex, deflection, speed (stuck)) - now this one is pretty great for a level 1 spell. It completely stops the target for a reasonable duration, and stuck is a decent debuff as well
Withdraw - while not technically a CC, when cast on summon or a party member it makes them completely invulnerable for a long duration and can be used to block passages. This was quite pivotal for my solo priest run. It has "cheese" written all over it however.
Level2:
Divine Mark (will -> deflection) This is both a decent single target damage spell and a good debuff, as deflection reduction is substantial. it's only problem is short range.
Instill doubt (will -> reflex, will, deflection) - Dazed is a pretty weak debuff on its own
Repulsing seal: (fort) -> (deflection, reflex, disable) - This target's fort, but since it's a hazard and hazard spells have increased accuracy this doesn't matter much as it will be enough usually
Level3:
Pillar of faith (fort) -> (deflection, reflex, disable). Damage is vs reflex and primary target only, while disable is aoe only. This is decent vs groups of mobs and can be used to clean up the ads, however this is not what we want to use on the dragon.
Despondent blows -> (will) -> (melee accuracy, crit -> hit). Not that great overall.
Level4:
Searing seal (will) -> (reflex, deflection, speed). Damage is vs reflex. Since it's a hazard it has increased accuracy, and it attacks will. Needless to say, this is the most reliable way to land blind in the whole game.
Shining beacon (will) -> (all), This is a damaging spell first and foremost, but -10 to all defenses is also nice. Short range is somewhat limiting, but it's still very much worth it.
Devotions of the faithful (will) -> (fort, accuracy, damage). This is both an excellent buff and debuff. it's one of the few ways to reduce fort even further stacking with weaken and -all saves spells. For example weaken + devotions + shining beacon = -54 fort. One thing to note that it does not have any +accuracy modifier itself. However, the buff part applies first (if you hit both yourself and the target with it), so if you're casting it for the first time, it will be cast at +20 effectively. it's max reachable accuracy is lower than some other spells however.
Level5:
None
Level6:
Cleansing Flame (deflection -> -positive effects duration). i've listed it here, but this is mostly a very powerful damaging spell, especially in combination with some others, so I'll describe it in more detail in damage section
Talents:
(Empowered) (Painful) Interdiction (will) -> (will, fort) - at 3 talents this is too big of an investment for solo, however applying weaken per encounter in an aoe at +25 accuracy is an excellent "breach" type ability and is definitely recommended in a party with other casters.
Ok, so basic debuff/CC combos:
Searing seal -> blind -> proceed with ref/def atacks. Not much of a combo .
Repulsing seal -> prone -> CC'd. This can actually miss due to the dragon's high fort if you forget to cast your buffs (so don't).
Interdiction + Devotions + Shining beacon -> will reduced, fort ruined.
Interdiction + Halt -> CC'd.
Interdiction + Divine mark - deflection lowered.
Buffs
A general note on buffs - stat buffs DO NOT STACK with food. However, they often provide 8 or even more points above what the best food offers, so they are extremely valuable and if you're planning to use them you can save money on food (or still use it as it has longer duration just in case).
Level 1:
Armor of faith - +4 DT at average speed is not bad for regular encounters, but for this fight it's too little too late
Blessing - Same as armor
Holy Meditation - Generally a good will & concentration buff, with great speed as well. You can use it as an extra layer of protection against will attacks, but not that impressive overall
Prayer against fear - as explained, this is a must have in dragon fights and it happens to be a priest spell
Level 2:
Holy power - Amounts to +7 deflection, +6 fort, +14 will, +21 concentration, +9% damage/heal. Not bad for its level but not too impressive later.
Suppress affliction - an obvious counter to afflictions, prevents DoT damage on you which is very good
Prayer against infirmity - another protection spell. Sicken and weaken do not happen THAT often, so it doesn't see light that much.
Level 3:
Circle of protection: +15 to all defenses is good, but base 10 second duration is just too low. You can have your priest just stand there and recast it for your party but solo it's not too useful. Generally Druid's moonwell (available as scrolls) is a bit weaker, but is better since it lasts much longer.
Dire blessing - 20% hits to crits. This is a decent damage buff, however it's not gamechanging. You can cast it if there's nothing more important to do. As a pro, it has fast cast speed.
Prayer against restraint - Stuck can be dangerous in some fights, but this is not one of them. Occasionally useful.
Level 4:
Devotions of the faithful - +20 accuracy that stacks with stuff like accuracy potions and scrolls, with +12% damage and +8 fort on top. Might bonus may be overridden by better buffs, but the accuracy bonus alone is worth it.
Prayer against bewilderment - This is a great counter to one of the most annoying afflictions. However it doesn't see any use in AD fight.
Triumph of the crusaders - fully restores endurance on kill (only once) for each affected ally. One of the best heals, but we don't want heals.
Level 5:
Champion's Boon - +20 fort and reflex, +10 deflection, +30% heal and damage, +30 interrupt and +5 DT. This is pretty great. it has average casting time and is a buff, so it's not the best option when you need to wreck faces immediately, but it's a very powerful offensive and defensive buff.
Prayer against imprisonment - a protection spell vs the scariest afflictions in the whole game.
Salvation of time - it's decent in a party with multiple ongoing buffs to keep them up, but worthless solo
Shields for the faithful - +25 deflection for a significant period of time is good if you want to max it out
Level 6:
Crowns for the faithful - this one amounts to +62 will, +31 deflection, +12 reflex, +75 concentration, +18 interrupt and +30% duration/+36% aoe. Needless to say it is very good. It's actually better than any prayer spell vs attacks that target will. And if you combine it with prayer immunity to these confusions/charms and dominates is almost guaranteed unless the recipient had like 3 int and res. Int bonus makes it the first buff you want to use, since it improves durations of all other buffs.
Minor Intercession: -5 duration of hostile effects - obviously useless solo, since you can't cast under the effects you want to shorten mostly. Marginally useful in a party.
Prayer against treachery - protection against charm and dominate - generally these are not the scariest afflictions solo, but it's useful in a party. Consider using crowns instead or stacking both though.
Basic buff combos:
Crowns for the faithful + any buffs = longer buff duration
Crowns for the faithful + prayer against treachery/bewilderment + holy meditation (probably an overkill) + circle of protection (definitely an overkill) = mind immunity
Crowns for the faithful + Champion's boon + Devotions of the faithful = power combo. +10 mig, +10 per, +6 Int, +25 res, +5 DT, +20 accuracy. Total save bonuses are +35 deflection +20 reflex, +20 fortitude and +62 will.
Champion's boon + prayer against imprisonment - +70 to saves vs paralyze/petrify
Tanking stats:
As mentioned before you ideally want 170+ in fort/def/ref to melee the dragon and a least 170+ ref to withstand breath. Alternatively you'll need to stay at the edge of LOS, but that's hardly tanking .
Let's check the standard wood elf priest. Stats 18/3/19/4/19/15.
Defenses by level 12:
Defl: 15 (base) + 33 (level) - 1 (stats) = 47.
Fort: 20 (base) + 33 (level) + 2 (stats) = 55
Ref: 20 (base) + 33 (level) + 6 (stats) = 59
Will: 20 (base) + 33 (level) + 28 (stats) = 81
With W&S style and exceptional small shield: D 69, F 55, R 81, W 81
With +10 to all saves and deflection rings or equivalent items: D 79, F 65, R 91, W 91
With +3 might, +3 dex, +2 per, +2 int items: D 81, F 71, R 101, W 95
(As PC): With gift from the machine, song of the heavens, berath's boon: D 83, F 73, R 103, W 97
So far no class specific stuff apart from 15 base deflection.
Let's use some buffs (crowns + boon):
as mentioned, +10 mig, per, +6 int, +25 res
D 128, F 93, R 123, W 159
Will is crazy, but other saves are still to low. What can we do? Let's use some items!
Potion of displaced image (+25 def, +20 ref)
D 153, F 93, R 143, W 159
We can also use moonwell scroll or circle of protection (it's better, but too short) for another +10/15, but that requires us to remain stationary. Alternatively we could do a 18/3/19/16/19/3 buid, which would suffer from low concentration (but we have buffs to solve that) for more ref. It will be D 153, F 93, R 167, W 159.
However, let's go with the standard build. Let's throw in a +4 Int rest bonus, and +2 Int/Per brother bonus even though it's not the best option for saves, along with +2 dex food.
D 155 F 93 R 151, W 171
Also, as wood elf we're getting +5 ref vs ranged attacks so effectively vs ranged we have:
D 155 F 93 R 151(6), W 171
14 short of 170 reflex mark. As mentioned we can use moonwell scroll, or we can land debuffs.
With blind (searing seal)
Effective D 180 F 118 R 176(181), W 196
With blind and devotions:
Effective D 200 F 138 R 196(201), W 216
As seen, we're still short on fort even with all this stuff, but we can reliably tank at range. What theoretically can be done to be able to tank in melee? We could use different rest bonuses, or transfer some points into CON, while also picking bear's fortitude. At theoretical 18 base con with bear's we'd have an effective 178 fortitude (so actually we can go with 14 con and say 4 res), but this is not too useful outside of theoretical study as this build won't be all that good in actual gameplay. So it's better to stay at range and use blind. Maybe go with a bit more balanced build 18/3/19/9/19/10 snatching another 10 reflex, which will make us just 4 short of 170 mark before blind, which can be covered with snake's reflexes or moonwell scroll if absolutely needed.
Damage
I won't go through all damage spells here, since they are pretty obvious, but will list the best here, along with some nuances.
Iconic projection - buffed up this easily does 30+ damage to everything in a line with no FF(if that matters to you) healing your party along the way (again if that matters to you). it also has fast speed, allowing to spam it. It can hit big targets multiple times, but I'd save it for the ads still as there are better spells for the dragon.
Divine mark - This is a decent single target damage spell as well as debuff, use it on the dragon if you need extra damage and can afford to get close.
Searing seal - use this for blind, but it deals some damage as well.
Shining beacon - awesome will targeting DoT. Despite AD having high burn resist, DoT ticks are reduced by only a fraction of original DT score (looks like about 25%), and maxed out this easily deals 30+ per tick.
Pillar of Holy Fire - again, despite high burn DT, this deals a lot of fire damage, hitting hard enough to be noticeable.
Cleansing flame - This is the best combo damage spell. There's a reason Thaos loves it. It doen't have any + accuracy modifier, so make sure to use all the buffs and deflection debuffs first (with these it's not difficult to land at all). Besides dealing heavy damage itself it speeds up other DoTs (shining beacon) by 100%, improving their damage greatly. Shining beacon + cleansing flame combo is enough to burn though most of the dragon's health. Needless to say, it's more awesome with other casters that use DoTs.
Honorable mentions: Pillar of Faith, Warding seal, Spark the Souls of the Righteous. These are all good, just not vs AD. Use them to clean up the ads. Sparks are great with figurine summons and have no attack roll (they always hit), but deal too little damage and the dragon has too much shock DT to make it useful.
Will add summary of priest tactics later. For now here's a vid link (execution is far from perfect, but you get the idea): https://www.youtube.com/watch?v=E3ENTVKRuqg&feature=youtu.be
To be continued with other classes...