Gravelgill Duo

Gravelgill Duo

Creature - Merfolk Rogue Warrior | Power/Toughness: 2 / 1 (CMC 3)
Whenever you cast a blue spell, Gravelgill Duo gets +1/+1 until end of turn.
Whenever you cast a black spell, Gravelgill Duo gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)