The Emerald Bat

Begin the game with this card revealed.
Chroma- Prevent the next {x} damage
that would be dealt to you (not lose life effect),
equal to the number of any one color of mana
symbols in the mana cost of permanents you
control. (Colorless can be chosen).
Pay {x} life: Prevent the next {x} damage that
would be dealt target creature you control.
You gain half of {x} that is prevented by this
role's Chroma ability.