Tefta, Soulcaster Savant

When Tefta, Soulcaster Savant enters the battlefield, exile the top three cards of your
library. You may cast instants and sorceries exiled
this way for as long as Tefta, Soulcaster Savant
remains on the battlefield.
Cards you own in exile have buyback {0}. (You
may pay an additional {0} as you cast this spell. If
you do, put this card into your hand as it resolves.)
"Existential dread is all that I have left."