Lucius, the Benevolent

When you gain life, you may pay {w}{u}. If
you do, reveal the top X cards of your library,
X being the amount of life gained. You may
cast a spell and play a land from the cards
revealed. Put the rest on the bottom of your
library. Activate only as a sorcery and only
once per turn.
"Among Heaven and Earth, I alone am the-"