I have defeated the vampire but I couldn't kill it because I surely don't have that bunch of wood with me. So I can't get the hand of that guy to remove the big head. The magical door wants three lighting stones but I was able to find only one.(A genie appeared and gave me an armor for that btw)
So what am I missing???

You can find a stake on the corpse of a kobold if you head west from the entrance in the northwest corner of the map on the level with the vampire. There's also another item in that part of the level that you'll need to complete the quest. The two missing stones for the portal are on the same level as the portal. Be sure to search carefully as there are some other nice items around there.