Congregation Gryff

• WOTC Official Reminder Textofficial rules
  Lifelink — Damage dealt by this creature also causes you to gain that much life.
• WOTC Official Reminder Textofficial rules
  Saddle — Tap any number of other untapped creatures you control with total power N or greater: This Mount becomes saddled until end of turn. Saddle only as a sorcery.

• WWizards of the Coast2024-04-12
  Official Ruling
  An ability that triggers when a creature “attacks while saddled” will trigger only if that creature was saddled when it was declared as an attacker.
• WWizards of the Coast2024-04-12
  Official Ruling
  “Saddled” isn’t an ability that a creature has. It’s just something true about that creature. It won’t stop being saddled until the turn ends or it leaves the battlefield.
• WWizards of the Coast2024-04-12
  Official Ruling
  If a permanent becomes a copy of a saddled Mount, the copy won’t be saddled.
• WWizards of the Coast2024-04-12
  Official Ruling
  Creatures with saddle can attack or block as normal even if they aren’t saddled.
• WWizards of the Coast2024-04-12
  Official Ruling
  You may activate a permanent’s saddle ability even if that permanent is already saddled.
• WWizards of the Coast2024-04-12
  Official Ruling
  “Saddle N” means “Tap any number of other untapped creatures you control with total power N or greater: This permanent becomes saddled until end of turn. Activate only as a sorcery.”
• WWizards of the Coast2024-04-12
  Official Ruling
  The value of X is determined as Congregation Gryff’s ability resolves. As long as Congregation Gryff is still on the battlefield at that time, X is likely to be at least 1.

Rulings via Scryfall