Moridin, Cruel Sovereign

Eminence— As long as Moridin, Cruel Sovereign
is on the battlefield or in the command zone,
whenever you play a creature spell you may pay {1}, if you do that creature gains riot.
Double strike, haste
{2}{w}{r}: Exile the top three cards of your library,
you may cast one creature, or equipment from
among them without paying its mana cost, put
the rest on the bottom of your library. This
ability can only be used once per turn.