The Lifetree

Legendary creatures you control get +2/+1.

Exile a legendary creature you control: Reveal the
top X cards of your library, where X is the exiled
creature's mana value. You may exile any number
of legendary creatures from among them, and put
the rest on the bottom of your library in any order.

You may cast spells exiled with The Lifetree by paying their mana cost reduced by {1}.