So what you do is simply save 20 fireballs which will cost a lot of gold but will be worth it. Then also save 12 healing potions and a magic portal. Go to the dungeon and go to the third floor and evade any monsters on the way. When you get to the Necromancer each turn shoot fireballs until he is dead if you get to low health then drink healing. You need 70 health to do this strategy ( best if you do ). Then when your all done say OPEN SESAMI. That's how I defeated him. Get information about the Evil Necromancer, click this link.[1]