Ethersworn Canonist
Artifact Creature — Human Cleric
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."
Izzy
Mystery Booster 2 (MB2)
• #10Rulings
Ethersworn Canonist takes into account spells that were cast earlier in the turn before Ethersworn Canonist entered the battlefield, including any spells that are somehow still on the stack. However, any spells on the stack as Ethersworn Canonist enters the battlefield have already been cast by that point, so they're not affected by it.
(wotc • 2020-08-07)
Each turn, each player can cast any number of artifact spells plus a maximum of one nonartifact spell.
(wotc • 2020-08-07)
Rulings
Ethersworn Canonist takes into account spells that were cast earlier in the turn before Ethersworn Canonist entered the battlefield, including any spells that are somehow still on the stack. However, any spells on the stack as Ethersworn Canonist enters the battlefield have already been cast by that point, so they're not affected by it.
(wotc • 2020-08-07)
Each turn, each player can cast any number of artifact spells plus a maximum of one nonartifact spell.
(wotc • 2020-08-07)