Best way to make this spell...

I want to make a spell that burns X life and Y mana over a period of time.

what is the best way to make this? i tried rejuvination but it doesn't give credit for the kill...

Off the top of my head. im thinking you could try these:

1. do a trigger :

Event : unit dies

condition : unit had buff

Action: you would need some sort of previous trigger that detects the caster then add exp manually to the owner.

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2. give the unit the buff of a modified phoenix fire that drains life and mana (along that road)

--------------------------------------------------------------------------------------------------------3. give the caster the life drain ability with no art or range so in effect as long as he casts, the unit will have life taken. but thats not what u want