Of course the necromancer is useless. A necromancer is, before anything else, a controller of undead. This undead can't be controlled, so his biggest ability is sealed. He tried one-hit kill magic on it that didn't work (not his fault). Any undead he summons isn't as strong as this one so will just eat an attack and die. He's actually being a big help with the healing.
Are any of you going to say that healers are useless? //Holy Pally