Spellbound Dragon

The looter clause is the engine and the threat at once. Most attack-triggered card filtering exists to smooth your draws and fuel a graveyard; here the discard does double duty, because whatever you pitch comes back as power on the body that swung. A 3/5 flier with a five-drop in hand becomes a 8/5 the moment it attacks, and the choice it forces is the whole interaction: keep the expensive bomb to cast it later, or feed it to the dragon for a sudden lethal swing. That tension makes the discard a resource rather than a cost. The plan rewards holding a fat, otherwise-clunky card (a top-end finisher, a colorless monster you can't yet pay for) specifically as ammunition, and it pairs naturally with cards that want to be in the graveyard anyway: flashback, dredge, reanimation targets, anything you'd happily discard for value. The 5 toughness is the quiet load-bearer, keeping the dragon alive through the kind of cheap removal that would punish a glass-cannon attacker before its trigger ever resolves. It dies to almost no chip damage, blocks well, and only grows when it goes on the offensive. A creature that turns your dead cards into damage and your good cards into a decision every combat step.