Siier, the Prodigal Riftborn

Convoke
{t}: Select an opponent's basic land, and
transform it into a colorless land. If that
opponent has only colorless lands, he/she
sacrifices one instead.
"I regret to say this, M'lady, but that wolf we let in is
a terrifying beast. Her power could rival this entire
city, could dwarf even yours. That crystal that she spreads, gives her complete and utter control over
anything it spreads to. M'lady, we should tread cautiously with this one."