Rule 420.4.a

Any such triggered abilities trigger when the act of playing the card has been completed by the resolution of the card.

• 420.4.a.1 If a game effect prevents the resolution of the card—for example, because the card was countered—abilities that…

Rulings that cite this rule

• I have a Ravenbloom Student on the board and I haven’t played any spells this turn. What happens when I play Rebuttal targeting my opponent’s Stupefy and pay [A] on resolution? After everything resolves, how much will Battering Ram cost? Will my opponent’s Legion abilities be active?

Official Core Rules