The Verdant Cadaver - Soulslike Boss Concept

ARTSTATION POST

A unique enemy/boss design for a hypothetical Soulslike game project.
Gameplay behaviours:
- I'm calling this design a boss, but I feel it would more than likely be entirely optional to fight it. You can walk up to it as close as you want, and it will only get up from its resting spot to attack once you hit it.
- Killing it would likely give the player some lore on Freesia or her religion, or perhaps reveal that there was a tiny shred of humanity somehow. Perhaps through an item drop or inspection of her boss arena now being possible? It would probably be the ring she was proposed to with that reveals the connection to Fericul to the player.
- Probably various poison attacks, be it status inflict melee attacks or AoE poison sprays.
- Donkey kick attack if player is behind.
- Hand/Claw slash swipe attack if player is in front.
- Possibly a grab attack? It is taller than the player.
- Probably no phase 2.
- Could also be a boss that never fights back - maybe only emits poison clouds at certain health levels, or summons fauna to its aid.
There's a lot more lore to this one, so I'll drop it here:
Context: Fericul is 
"The Verdant Cadaver is a failed attempt of Fericul's at resurrecting Freesia - his fiancée. Much in contrast to him, a man of science, she was deeply religious. Her religion believed that nature was alive itself, no different from humans, and its embodiment was a blend of deer and human - a regal creature. Through prayer to land, they'd attain bountiful harvests. Through prayer to the trees, they'd be gifted with shed branches that formed into the shape of gardening tools. They prayed to nature, and nature responded with gifts.
When Freesia was unexpectedly killed by an ambush in her travels, Fericul was distraught. He started looking to any and all measures to bring Freesia back, be it by science or esotericism. Believing he found a solution, he attempted to resurrect Freesia. As it would turn out, the ritual would only bring back the body, not the soul. From the shreds of memory left within the body, it would morph and shift. It absorbed the flora by which it was buried and become a mockery of the god Freesia once followed. Instead of bringing bountiful harvests and lush fruits, this creature is coated in poisonous fungi and toxic flora."