Aspect of the Twisted Soul
Aspect of the Twisted Soul has 1,700 health.
It resists pierce and fire; poison does nothing to it at all. Blunt and slash land at full damage, so that is what to bring.
Nothing but a player can damage it, so tames, Dvergr and summoned companions do nothing for this part of the fight.
Its hardest hit is goblin king nova at 90 lightning and 75 fire, out of 2 attacks.
Some of what it throws is elemental, so fire and lightning resistance is worth having.
Of everything craftable, 
Lightning Strike, 
Frostfire Sledge and 
Frostfire Greatsword put the most damage through what it resists.
Aspect of the Twisted Soul is a phantom copy of 
Yagluth that 
Kall Fimbulbringer summons during his second phase. It has 1,700 health, is very resistant to pierce, resistant to fire and immune to poison, leaving blunt, slash, frost and lightning at full value. It drags itself along on its hands at a walk speed of 5 and a run speed of 4, so charging is the slower of its two gaits. Only players can hurt it, and it drops nothing.
Very resistant to pierce and resistant to fire, so bows and anything burning are the wrong tools. Blunt, slash and lightning all land at full. It is the slowest of the seven at run speed 4, which makes it the aspect you can safely leave for last while you clear the faster ones.
With devcommands enabled, this spawns Aspect of the Twisted Soul in front of you. The third number is the level: 3 spawns a 2-star.
Creature ID: Aspect_Yagluth · all console commands and IDs