You see a snail slime.
Notes
Fire Damage will heal it. It looks like a Slime.
Abilities
Unknown.
Damage Taken From Elements
Physical 
Death 
Holy 
Ice 
Fire
Energy
Earth
Drown
Location
Warzone 5 inside the boss rooms.
Behaviour
They fight in close combat.
Strategy
Lure it far from The Count of the Core and kill it.