Creating a Raise Dead spell

[matte 2]

Yo wassup party people, was wondering if any of the big brained minds on these forums knew anything about creating a 'raise dead' spell, similar to the death knight one from WotLK. What I want to do is trigger a check when the spell is cast to see if there are any humanoid corpses around and, if so, create a minion through the nearest one (and causing the corpse to disappear). Unlike the original spell, I want to have more than one minion up at a time, and I want different spells to trigger the creation of different types of minions through corpses. I tried using the original Raise Dead as a basis, but no matter what happens, the spell can only be used once and then won't ever reset its cooldown. Help would be appreciated.