Triskaidekaphobia

At the beginning of your upkeep, choose one —
• Each player with exactly 13 life loses the game,
then each player gains 1 life.
• Each player with exactly 13 life loses the game,
then each player loses 1 life.
With each leaf, another innocent soul falls to the
Cursed Rebirth. Be careful with your meddlings
though, for you may be the one who falls victim
instead.