Arcane bombardment

Whenever you cast your first instant or sorcery
spell each turn, exile an instant or sorcery card at random from your graveyard. Then copy each
card exiled with Arcane Bombardment. You may
cast any number of the copies without paying
their mana costs.
"Everything is warped, lands are merged and
destroyed. Asteroids and celestial bodies plummet to
crash on the horizon. Must be Tuesday" - A denizen
of the upper levels of Valakut.