Displacement Attacks
In chess, a displacement attack drags a defender away from the piece it guards, allowing a capture of a previously guarded piece. Usually this involves a sacrifice, a check, or both. Black to move:
FEN 6k1/2b3p1/p7/2rp4/8/P1P2P2/1B1qQK2/5R2 b - - 6 1
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Bg3+ delivers a huge advantage for Black, as the White King may only capture the Bishop, or less ideally flee to g1. This removes the White King as the only defender of the Queen, allowing Black to capture the Queen for a sizable advantage.
This position is based on a Chess Ladder game at work (25 minute games played over lunch with a chess timer), and mistakes were made on both sides, as either Black had a mate-in-four involving the rook (or a longer mate-in-six with the Bishop check) or the White King could have migrated safely to f3 (hence there being a Pawn there now), but I cannot remember the exact position or what better moves were missed at the end.
Speaking of Chess Ladders, the largest problem is that the same people end up playing one another, and a joiner will fairly quickly rise to their skill level, and usually play the same two to three people week after week. Perhaps with a larger chess ladder, more players of equivalent rank would allow for more frequent changes in position?