Unleash the Sandstorm!

Affinity for Deserts (This spell costs you {1} less to
cast for each Desert you control.)
Destroy all creatures you don't control. If four or
five mana was spent to cast Unleash the
Sandstorm!, destroy all creatures instead. If three
or less mana was spent to cast Unleash the
Sandstorm!, destroy all creatures you control
instead.
Flashback {3}{w}{w}, Sacrifice a Desert