Rinshimo, Serpent's Touch

Whenever you cast a blue spell, you may tap up
to one target permanent. If that permanent has a
mana value that is less than your spell's mana
value, put a stun counter on that permanent.
Whenever you cast a black spell, you may destroy
up to one target tapped nonland permanent with
a mana value less than that spell's mana value.
Whenever you cast a green spell, you may gain
life equal to that spell's mana value.