Roll initiative!

All players roll a D20 (a 20 sided die). The player
that rolls the highest becomes the DM.
If there's a tie between two or more players,
repeat the process until there's a clear winner.
When a player becomes the DM, he or she rolls a
D20 for each other player in the game.
Players lose Life equal to the results of the die roll.
If the result equals 20, the DM wins the game. If
the result equals 1, the DM loses the game.
"Ready your weapons, and ready your dice!"