Ghitu Fire-Eater

The conceit is a creature that converts itself into a burn spell on your terms, and the activation cost is where the slot earns its identity. The damage comes from an activated ability, not a death trigger, which is why the body is rarely wasted: when an opponent points removal at it, respond by activating in answer to that spell and cash the creature in before it resolves, taking your burn either way. What keeps the card honest is the tap requirement. It cannot be sacrificed the turn it enters, so the burn arrives a turn behind the body rather than functioning as a flash answer the moment it lands; the threat has to survive a rotation before it pays out. Bank the result for a stranded creature, a planeswalker that just ticked up, or the last few points off an opponent, or hold it back as a blocker they have to evaluate against a 2/2 that can flip into Shock at instant speed. The genuinely open part of the design is that the damage scales to power rather than to a fixed number, so any pump effect turns the same sacrifice into a larger burn: that scaling is the door a fixed wording would have closed. Most of the time it reads as a fragile body with a deferred burn spell stapled on, and that modest framing is the point. The payoff lives in patience, banking the activation until the moment it matters, then spending the creature to cash it in.