The Collector

The Collector "lives solely to collect all kinds of rare gems, crystals and minerals. Offering an item it does not already own, reportedly allows passage into its lair." (Spectulus).

The Collector will retreat at 1 to 13 (0.29% - 3.82%, deep red) health.

Knights with 50/50 with the equipment given to you on Island of Destiny will be able to kill it. - Sorcerers, Druids and Paladins should get distance from it and kill it while running. Try to always keep walking on the ice, so it won't hurt you. Be careful Low-Level players, his attacks really hurt.