Historical Rules · 1 May 2013
Rule 801.18
Official source text from the 1 May 2013 Rules release
If the game somehow enters a "loop" of mandatory actions, repeating a sequence of events with no way to stop, the game is a draw for each player who controls an object that's involved in that loop, as well as for each player within the range of influence of any of those players. They leave the game. All remaining players continue to play the game.