Inkfathom Witch [Planechase 2012]

Cost: 1 U/B Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
2 U B : Each unblocked creature has base power and toughness 4/1 until end of turn. The murk of the Wanderbrine concealed unseemly rituals designed to bring out the worst in merrowkind.