Alright, first, you must talk to the 'half-orc' that is apparently permanently stationed in the Arena Bloodworks. Speak to him about 'the gray prince'. He gives you a quest. Fast Travel to Anvil and go north east. You will arrive at the what appears to be a tomb, and there are several skeletons scattered around the ground. Pick them off and head inside. You will be attacked by quite alot of wolves in here, but follow the marker. Do not go to the downer levels unless you want to fight some vampires. When you get to the locked door, you use the key that the orc gave you. His vampiric father is inside, 5 levels above your own but only armed with a dagger. Pick him off, he is easy, then head to the other side of the mist, his journal is there, revealing that he is indeed a vampire. Take this back to the half orc, and he goes into depression. When you fight him in the arena, he begs you to kill him, and there you go.. an easy win.