You see The Sinister Hermit.
Notes
Part of the Cults of Tibia Quest.
Abilities
Melee (0-1100+)
Terra Beam (300-400?)Damage Taken From Elements
Physical 
Death 
Holy
Ice
Fire
Energy
Earth
Drown
Location
The Humans Cult hideout under the Outlaw Camp.
Behaviour
Fights in close combat.
Strategy
While it's in this form the boss is vulnerable. Dealing damage to it while it is not standing on the geyser will cause it to turn back into it's invulnerable form, The Sinister Hermit (Yellow).