Decoy is a piece sacrifice in chess made in order to get an advantage by forcing the opponent piece to change its position.

Let's see an example.
Diagram 1 decoy

1. Qh7 Queen sacrifice by White. Black King is obligated to capture the Queen.
If not 1. ... Kf8 2. Qh8 checkmate.

Diagram 2 decoy2

After King captures the Queen , Discovered check by Bishop . Rook controls the escape squares of the opponent King.
1. ... Kxh7 2. Re8 mate.

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