The War Within

If this spell was cast in a Magic subgame, end
the subgame and you win the game. Otherwise, players play a Magic subgame starting at 5 life
with a card of each type from their main-game battlefield on the battlefield. The winner returns
their chosen cards to the battlefield under their control rather than shuffling them into their
owner's library. If you're the winner, return each player's chosen cards to the battlefield under
your control instead.