Whenever you capture a piece, you receive an additional pawn and place it "in reserve" outside of the board. On your turn, instead of moving, you may place any pawn that you have in reserve on the board, provided that it does not put any player in check, it cannot promote, and it cannot immediately move to a square where it can promote.

First appearance: 01/21/07 (0.5.0 release of rules).
Tags: Time Bomb power