In Warlock Chess the rooks are replaced by "Warlocks", otherwise it's
the same as orthochess. This new piece can change movement capability
by using up a move to transform itself. A Warlock rook can change into
a Warlock cannon by turning the rook upside down, or vice versa. The
Warlock cannon uses Korean Cannon movement: it moves as a rook after
having jumped a piece. If it cannot jump then it cannot move. As such,
it is somewhat weaker than a knight, but its tactical capacity is
great. In any case, the Warlock cannon can always transform itself
back into a Warlock rook. After the piece is transformed it must make
a move before making yet another transformation. So it's not possible
to stay put and make continual transformations on the same square.

This is a minute change to standard chess, yet it introduces many new
tactical elements. The Warlock has great attacking potential, and it's
much easier to maneuvre than the clumsy rook. But it costs time to
transform it back and forth.

http://hem.passagen.se/melki9/warlockchess.htm

Mats