At the end of your turn, you can sink or raise (un-sink) one unoccupied square. Sunken squares may be entered or crossed only by royal pieces or by pieces whose only moves would require them to move through sunken squares. There may not be more than 10 sunken squares at any time.

First appearance: 1st Design Competition (1st place in 5-way tie, 2nd place finalist in tiebreaker).
Creator: Alex Nisnevich
Tags: Interruption power