Beast of Winter DLC boss fight

[Destinyblade]

Does anyone have any specific strategies or tips for this fight? I thought I had this fight but she kept healing from the Siphon spell that it eventually didn't work.

Is there any way to stop the dragon from using Concelhaut's Corrosive Siphon? or negate it

[xzar_monty]

You can always interrupt spell-casting. As for general strategies, check what kind of damage the dragon is most and least vulnerable to.

[Boeroer]

Search for abilities that cause interrupts or prone (basically an interrupt+).
For example Thrust of Tattered Veils or Slicken (Wizard, ToTV is even an auto-hit ability), Knockdown (Fighter), Crippling Strike (Rogue) and so on.
It's mentioned in the description if the ability/spell does cause an interrupt or not. 

Normal auto-attacks will not interrupt anything unless you have a weapon that can interrupts by itself (uniques or some modals). 

You can also use weapon proficiencies or in other words weapon modals such as crossbow or arbalest to cause interrupts.

Note that Concentration will counter an interrupt. If you hover over Neriscyrlas in battle you can see the layers of Concentration she still has (she has a lot). You can completely remove all Concentration with a chant (Thick Grew Their Tongues) or with something like Plague of Insects or Insect Swarm. Or you can remove the layers one by one with interrupts (a few hits from Slicken, some hits with a crossbow + modal etc.). Once the Concentration is gone your interrupts will stop her spells and abilities from manifesting. 

If you manage to hit her with a terrify effect (for example Fear Ward from Furyshaper, Ryngrim's spells from Wizard etc.) she will become "only" frightened - but that's still enough to prevent her from using any offensive abilites (including spells) against you as long as she is frightened.

 

[thelee]

4 hours ago, Destinyblade said:

Does anyone have any specific strategies or tips for this fight? I thought I had this fight but she kept healing from the Siphon spell that it eventually didn't work.

Is there any way to stop the dragon from using Concelhaut's Corrosive Siphon? or negate it

on top of what other people said:

 

spread out

 

you can see when the dragon is prepping a spell, and separate everyone you can. one siphon target is much easier to out-dmage versus an entire party's worth.

part of also what might be contrbiuting to siphon messing you up is if you let llengrath's safeguard take place - which will massively boost Ner's defenses and make it hard to overpower a HoT. same strategies for interrupt. You can also use tranquilizing shot to cleanse it (best solution for most annoying boss tactics), or try your luck with club modal and arcane dampener.

[Helz]

Concelhaut's Crushing Doom is another nice one for interrupting bosses. It looks funny on dragons too because sometimes they don't fall down and get frozen in silly positions instead.