Ball of Green Slime

Whenever a creature you control goes to your graveyard, lose three life. Green spells you cast cost (G) less to cast. (T): Put a +1/+1 counter on target creature that doesn't already have one. (T): Add (G)(G) to your mana pool.
This stuff could benefit us in so many ways...but then again, guns are used to kill people so you'll probably run into a dead guy at some point.