In Mad Elephant Chess a player may as their move convert a Pawn into an Elephant (also known as an Alfil, which means "The Elephant" in Arabic). Elephants in turn, may upon reaching the back two rows promote to Mad Elephants, which can rampage, capturing all the pieces in a line in front of it. The object of the game is the capture, not checkmate of the King, and Pawns can taunt their opponent's Mad Elephants, causing them to trample the taunting Pawn (and even to trample either side's King!). Elephants and Mad Elephants replace the Bishops.
 
A longer, more detailed description of Mad Elephant Chess can be found at http://www.chessvariants.com/diffmove.dir/mad-elephant.html.