Ethersworn Canonist - 10 R ALA

Each player who has cast a nonartifact spell this turn can't cast additional nonartifact spells.
"The noble work of our order is to infuse all life on Esper with etherium. Our goal will be reached more rapidly if new life is . . . suppressed."
rare
Artifact Creature — Human Cleric
From the Magic: The Gathering set Shards of Alara.