He is by far the most powerful creature in the game, but he can be beaten. You will need to pay close attention to which damage types are effective against him. I recommend radiant damage, but you can try out powers that deal different types of damage and see what works. You can also try using Amplify damage to lower his resistance to the elemental damage types (fire, cold, acid, lightning). What powers and skills do you have currently? What damage types have you tried?
Here are some ideas:
Take the skills in the Necromancy discipline tree (Necromantic Mana, Necromantic Strength, Necromantic Power). This will give you a huge boost to damage for each creature you have killed in the last 10 turns (which at this level could translate into more like 20 – 30 opportunities for you to act since you probably have a speed between 20 and 30 by now). You can rack up huge kill counts in the vaults (the red areas that are packed with creatures). Chain Reaction or Chain Lightning are a couple of good options for racking up massive kill counts quickly. It takes some careful planning to do it in a way that doesn’t kill you. Ghost Walker is nice for being able to pop in and out of walls to escape from dangerous situations. Be careful not to try teleporting when near Drazul or when near an Anchoring rune, as you will get debuffs and the teleport will fail. Buff up with as many potions as possible (which ones you need depends on your equipment). I highly recommend Hidden Light as it allows you to still use a light source with potentially very useful bonuses, without having to worry about giving away your position to every creature in line of sight. Supernatural Recovery and Supernatural Luck, along with some items that give bonuses to saving throws will be very important for preventing you from being stun locked. Some of these things you may have figured out already since you got this far.
Thanks for playing!
Amon
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