Gift of Fangs

A single black mana buys a card that reads two opposite ways depending on where it lands. Point it at your own Vampire and it is a cheap, aggressive pump: +2/+2 for a one-mana Aura is exactly the rate a tribal aggro deck wants, and it stacks the way tribal payoffs are supposed to. Point it at anything else and the same Aura becomes removal, dropping a creature's toughness by two and often killing it outright. The design trick is that both halves live on one card without a mode to choose: the enchant target decides which spell you cast. That solves the perennial problem with tribal buff spells, which is that they sit dead in hand when the board has no creatures of the type worth enchanting. Here there is almost always a legal target, because enemy creatures are targets too, and pointing the Aura at them turns a whiffed pump into a kill. The obvious tension is that the -2/-2 punishes any of your own non-Vampires that stray into range, so the card wants a board that is Vampires or nothing. Being sorcery-speed keeps it honest as removal: you commit it on your own turn, without the ambush window that would make a one-mana toughness-shrinker oppressive. It is a small, tidy piece of type-matters design: a buff and a kill spell folded into the same mana cost, with the creature type doing all the sorting.