Blight-Breath Catoblepas is a removal spell on a stick that, by default, kills creatures with 2 points of toughness, which isn't bad. But if you can get this spell to remove something bigger with the help of other black permanents, then you're in good shape.
Again, it all depends on your devotion to black color, which will require you to have some black cards on board. But since Blight-Breath Catoblepas costs 6 mana, you most likely will have something in play by turn six. So this one should be on your radar for sure.