Gri'lek (original)

Gri'lek is a former dire troll berserker who is now a ghost. He is one of several bosses which can spawn during the Edge of Madness event within Zul'Gurub.

Background
A bit of Gri'lek's story is told in Tale of Gri'lek the Wanderer, part 2 of Troll Legends. Also, a book about Gri'lek is the objective of.

Strategy
Half of the time, you can fight him as you would any other melee mob (although he is immune to taunt).

The other half of the time he uses his unique special ability: his size doubles, and his attacks increase dramatically in damage (5000+ on average). This also causes him to wipe all previously accumulated threat. However, while in this form his movement is dramatically slowed. He announces which player he has targeted, so everyone should be ready to run if they see their name spoken. He also has a tremor ability which causes stun effects in an area around him. At least one priest or paladin should be assigned to dispelling any root effects which strike Gri'lek's current target, to ensure that Gri'lek does not catch and one-shot him.

Note as of Patch 1.10.2, he will not fixate on a single target while enraged. Recommendation is play pingpong with him.