Gryff Rider
Creature — Human Knight
Flying
Training (Whenever this creature attacks with another creature with greater power, put a +1/+1 counter on this creature.)
"Keep your heels down and bend at the hips as your mount takes flight. She'll do the rest." —Anders, cathar drillmaster
Yongjae Choi
Rulings
A creature's training ability triggers only when both that creature and a creature with greater power are declared as attackers. Increasing a creature's power after attackers are declared won't cause a training ability to trigger.
(wotc • 2021-11-19)
Once a creature's training ability has triggered, destroying the other attacking creature or reducing its power won't stop the creature with training from getting a +1/+1 counter.
(wotc • 2021-11-19)
Rulings
A creature's training ability triggers only when both that creature and a creature with greater power are declared as attackers. Increasing a creature's power after attackers are declared won't cause a training ability to trigger.
(wotc • 2021-11-19)
Once a creature's training ability has triggered, destroying the other attacking creature or reducing its power won't stop the creature with training from getting a +1/+1 counter.
(wotc • 2021-11-19)