Rethilgore

Rethilgore, having already been killed in the past, has a chance to be summoned as a ghost worgen by Baron Silverlaine when his health is brought to ~25%.

Background
Prior to being killed, he was one of the most vicious worgen, entrusted by Archmage Arugal to guard the prisoners who have been caught breaking into Shadowfang Keep. These included Deathstalker Adamant, Sorcerer Ashcrombe and Landen Stilwell.

Strategy
Rethilgore is not very hard to kill. He does 54-62 physical damage in melee, mitigated by armor. He will cast Soul Drain, which immobilizes a player for 10 seconds and drains 35 health, healing himself with it. Easiest way to beat him is to just bring him down with attacks and spells. Look out for worgs and wolves around him. They are weak so kill them quickly and finish Rethilgore.