At the other side of the teleporter. The teleporter to him is at the way to the place where it spawned before the Killing in the Name of... Quest was introduced to Tibia- only it's one floor further down. It is also marked when you complete the task of killing 5000 minotaurs so it isn't hard to find.
Mages: Kill him fast with Ice Strike or Death Strike so you won't get much damage from him nor his summons. Ideally, use Invisibility so as not to receive any damage from his summons (if he has time to summon).
Knights: Try to trap him in a corner so you know where he is when he goes invisible. When he goes invisible use Berserk. Use Stealth Ring so you don't receive damage from his summons. Paladins: Kill him fast and use Invisibility so you don't receive damage from his summons. Further, it is recommended that you run him so as to minimise damage.