Rain from the Heavens

Stockpile {1}{w} ({1}{w}, Exile this card from your
hand with a cache counter on it: It gains "{1}{w}: Put
a cache counter on this card." and "You may cast this
card from exile with its cost reduced by {1} for each
cache counter on it.")
Destroy all creatures. If this spell was cast with no cache counters on it, you may put all creatures
on the bottom of their owner's libraries instead.