Aspect of the Living Forest
Aspect of the Living Forest has 1,600 health.
It takes extra damage from fire; poison and spirit do nothing to it at all. Blunt, slash and pierce 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 gd king stomp at 150 blunt, out of 2 attacks.
Of everything craftable, 
Staff of Embers, 
Frostfire Crossbow and 
Thunderblood Crossbow put the most damage through what it resists.
Aspect of the Living Forest is a phantom copy of 
The Elder that 
Kall Fimbulbringer summons during his second phase. It has 1,600 health and is very weak to fire, the sharpest elemental weakness of any aspect, while poison and spirit damage do nothing to it. It runs at 6 and swims at 1.5, the slowest swimmer of the seven, and like the rest it can only be hurt by players.
Very weak to fire and immune to poison and spirit, which is the same answer that worked the first time you fought it. Anything with fire on it, the Frostfire line included, cuts through the health bar fast. It is immobile enough that the root volley is the only thing that reaches you at range.
With devcommands enabled, this spawns Aspect of the Living Forest in front of you. The third number is the level: 3 spawns a 2-star.
Creature ID: Aspect_Elder · all console commands and IDs