Aegar's Gauntlet

Whenever a Giant or Wizard creature you
control becomes the target of an opponent's
ability or spell you may deal 3 damage to that
opponent.
Whenever you cast a Giant or Wizard spell,
Aegar's Gauntlet deals damage equal to that
spell's converted mana cost to target creature or
planeswalker. If a target is dealt excess damage
this way, repeat this ability.