Desperado
A doomed piece that, before being lost, captures as much enemy material as possible.
A desperado is a piece that knows it is lost. Its capture is unavoidable on the next move — perhaps it is attacked twice, perhaps it is in a fork it cannot escape — so before going to the board’s pile of captured pieces, it does as much damage as it can. It captures enemy material, even at the cost of being recaptured.
The motif appears most often in tactical sequences where two pieces are both attacked and only one can be saved. The piece that cannot be saved is often better off capturing something on the way out than simply waiting to be taken. A knight about to be captured by a pawn might first take an enemy bishop; even if the knight is then taken, the trade has been favourable.
The desperado is also a defensive resource. A pinned piece that is going to be lost anyway can sometimes still deliver a check or capture an important piece before being captured itself. Strong players evaluate every doomed piece as a potential desperado before accepting that it is simply lost.
The Spanish word — meaning one without hope — captures the situation exactly. The piece has nothing to lose. It can take whatever it pleases on its way to oblivion.