The Comeuppance of Commeuppance
Since Purphoros doesn't have enough devotion to make him a creature there is indeed a loop, but it's not a loss for any player, but a draw:


  104.4b If a game that’s not using the limited range of influence option (including a two-player game) somehow enters a “loop” of mandatory actions, repeating a sequence of events with no way to stop, the game is a draw. Loops that contain an optional action don’t result in a draw.