Attack-in-the-Box

The pun is the design brief: the jack pops out, swings hard, and doesn't go back in the box. The default body is a 2/4, a passable blocker that trades up and holds a flank indefinitely, and that is the pose it can hold turn after turn for free. The attack trigger sets up the negotiation: opt into +4/+0 and you have a 6/4 for a single swing, but committing to the pump commits the creature to the graveyard at the next end step. That is a genuine per-turn decision rather than a one-time detonation, because you attack as a plain 2/4 as often as you like and only cash in the burst when the six damage actually closes something out. The finality is self-imposed and delayed to the end step, which leaves a real window: the card survives the combat it powered up for, so it trades in that fight, connects for the swing, and only then dies. That delay is also the exploitable seam. A sacrifice outlet fired in response converts the doomed body into whatever the outlet pays out, taking value before the pump's own sacrifice can, while a blink effect after combat strands the delayed trigger entirely and returns the creature ready to swing again. The rate is honest for what it is: a defensive piece that stores a burst of reach for the turn the board finally cracks open, sold to you at the price of the creature itself.