a goblin headmaster  

Just to clarify where he spawns so you don't look for him or have to kill the whole island like I did :). He spawns at loc -1203, -8567, right in front of the tent slightly to the left of the opening. Some times there is a place holder there.

I camped the Goblin Headmaster last night. He lives on the same island as the Oracle. At level 31, all the goblins on the island con'ed green to me except the headmaster and the headhunter. Those two con'ed blue to me. I was able to pull the headmaster without aggro-ing the other of the the isle goblins around him. The isle goblin shamans do however heal the headmaster once he drops below half health if they are in range to cast. Their healing spells I found do not heal a significant amount. I killed him 3 times. He dropped the shadowed knife once, the chipped boned mask once, and the rune of clay twice. All were no drop items. He also respawned alway in the same place. The spawn rate was around 5 mintues.

yes, this dude does drop the acumen mask item called a chipped bone mask. which i need also (time to head on over to oot!)

This fella also drops the runes of clay needed for the magician's Solusek Ro quest. He spawns near the tend on the oracle island.