Margaret, Velvet Attendant

Whenever a spell or ability an opponent controls
would counter, target, or exile a spell or ability
you control, you may pay {2}{u}{u}{u}. If you do,
take an extra turn after this one.
{w}{w}{u}{u}{b}{b}{r}{r}{g}{g}, Pay 50 life, {t}: Each opponent loses the game. Activate this ability
only after twenty or more turns have passed.