Friendship's End

Split Second
Permanents opponent's control loses hexproof
until end of turn. Then exile target permanent.
Its controller loses 4 life and discards 3 cards.
Exile Friendship's End with a regret counter on it.
At the beginning of your upkeep, put a regret
counter on Friendship's End. Then if Friendship's
End has 5 or more regret counters, then you lose
the game.