First thing you should do is dump the resolve. Everything hits you on PotD. Keep Con low and learn to focus on certain stats instead. What you need for PoE2 is armour rating, decent deflection so you don't get autocrit 24/7 and high reflex/fortitude/will ,in that order.
Roughly 130-140 for decent survivability on PotD. 150+ makes you unkillable. If you wish to play a dps druid that melees and cast spells, you should probably ask yourself what is your main source of damage. Elemental spells? Melee Weapons? Summons?
If you plan on using elemental spells to kill stuff but still want to keep some semblance of melee capabilities. I suggest going fighter as your multi-class. Their level one can be upgraded to give +1 power levels while boosting the accuracy of your own melee attacks. Their aura gives +5 accuracy to your spells as well. Overall, they have pretty decent fast cast melee attack/defense abilities that won't affect your spell casting too much. Eg. charge for positioning and an instant attack. buffs are instant with no recovery. Mob stance gives faster recovery as well and great for clearing mobs that were weakened by your spells.
For something more spell focused, chanter would be best but then it is kind of op right now. Priest is a decent choice with their buffs +acc/+power level etc.
For something more weapon focused with druid acting as the support, you can consider a bleak walker or just fighter. Monk is great too but it is kinda op right now. Bleak Walker will give you all the defence you will ever need to charge in with a two-hander, double or single weapon. Just spam Flames of Devotion for damage and use cold druid spells to supplement your lack of damage diversity. Their aura helps your spells as well.
In general, just ask yourself can your build deal at least two damage types, does it have a sustainable source of damage with empower included (final boss has 2 phases. Bosses like Nemnok have a ton of hp.) Does your build have a way to handle large mobs/does it have a way of pulling mobs if it can't aoe?
This is assuming you are running solo potd. If it's a team build, just go paladin and go full spell spammer. Lay on Hands is all the heal you will ever need.