You see a possessed tree
Notes
It looks like a Haunted Treeling. It can be destroyed by the Mounted Thorn Knight in one blow.
Abilities
Melee (0-162+)
Poison missile (0-86+)Damage Taken From Elements
Physical 
Death 
Holy
Ice
Fire
Energy
Earth
Location
A dungeon here, accessible through the Desecrated Glade.
Behaviour
Unknown
Strategy
Unknown