Sandy, Sometimes Sentinel

— Opponents cast spells face down.
Whenever an opponent casts a spell you may pay
{1} and tap, Sandy, Sometimes Sentinel, then
reveal the spell.
If you paid {1} and tapped Sandy, if it was a
creature spell, untap all permantns you control
and draw a card. If it was a non-creature spell,
Sandy, Sometimes, Sentinel does not untap
during your next untap phase.