In Thrall to the Pit

Threaten effects have always carried a built-in expiration: the borrowed creature returns home when the turn ends, so you get one attack step to convert the loan into damage or value before the window shuts. At its splashless price, this is exactly that: a sorcery-speed steal that untaps the target, grants haste, and spends a burst of tempo on your own turn. The black kicker is where the calculus changes, folding a removal spell into the theft: pay the splash and the creature is sacrificed at the next end step rather than handed back. That is the design's real trick, and it pulls the card toward Rakdos rather than leaving it mono-red. Red can borrow anything, but it cannot cleanly finish the job on a creature it does not own; the black portion of the cost is what buys the sacrifice and lets a single card pull double duty as tempo swing and permanent answer. The kicker does not replace the steal, it appends to it: you still get the attack, and then the creature dies instead of reverting, so the choice is really how much you want to pay to keep the loan from coming due. Unkicked, it is a cheap swing when you are racing and a sacrifice outlet can eat the creature before it reverts anyway. Kicked, the spell handles that removal internally, no outlet required. One card, two prices, and the problem you are solving determines which you pay.