Elven Chess is a game on a 10x10 board that supplements the FIDE army with 4 types of new pieces

Elven Chess is basically a translation of the historic Japanese game Chu Shogi to a FIDE context, shrinking it to a smaller (but still 10x10) board with fewer pieces.

Elven Chess involves 13 pieces behind a rank of 10 Pawns. The 5 new pieces differ from their orthodox counterparts by also being able to move and capture like a King. The strongest of these (the Warlock) is essentially a King that can move (and capture!) twice per turn, and is far stronger than a Queen.

There is a rule against trading Warlocks easily out of the game, forbidding the capture of a Warlock on consecutive moves; either the first capture is already forbidden (when recapture on the same square is possible), or the second (when that takes place on a different square.-).