Marit Lage's Slumber

Whenever Marit Lage's Slumber or another
snow permanent enters the battlefield under
your control, scry 1.
At the beginning of your upkeep, if you control
ten or more snow permanents, sacrifice Marit
Lage's Slumber. If you do, create Marit Lage, a
legendary 20/20 black Avatar creature token
with flying and indestructible.