Venomous Devourer

When Venomous Devourer enters the battlefield,
target nonartifact creature gets -2/-2 until end of
turn if {b} was spent to cast Venomous Devourer.
When Venomous Devourer enters the battlefield,
you gain 4 life if {g} was spent to cast
Venomous Devourer.
Evoke {b/g} (You may cast this spell for its evoke cost.
If you do, it's sacrificed when it enters the battlefield.)