Marn, Harbinger of Oblivion

Distort, Forbidden
If 10 or more cards were put into exile
from anywhere this turn, until end of turn you
may cast Marn, Harbinger of Oblivion from
exile.
{t}: Add {c} for each land card in exile.
{c}{c}: Exile the top two cards of target player's
library.
{c}{c}{c}{c}{c}: Creatures opponents control with
power 3 or less cannot block this turn.