In a land of wizards, disputes were settled by magic duels. Often, these duels were fierce, with powerful magics casts against the other. The results were often disastrous and deadly in heated duels.
Such were the fears of an ancient king. Among his most trusted advisors were two sorcerers that hated each other with a passion. They had dueled many times, each time more brutal than the next. To keep them both alive he decreed that magic duels would be settled by magic proxy.
The duelists would conjure a magic construct, which they would control against the other. The constructs, or marionettes, would do battle trying to win by one of three ways. One, subdue your opponent in such a way that it cannot continue fighting. Two, outlast or force your opponent to exhaust their magic reserves until they lose form and revert back to its marionette crystal form. Or three, outright killing your enemy.