Sapling Nursery

• WOTC Official Reminder Textofficial rules
  Affinity — This spell costs less to cast for each [quality] you control.

• WWizards of the Coast2025-11-17
  Official Ruling
  Whenever a land you control enters, each landfall ability of the permanents you control will trigger. You can put them on the stack in any order. The last ability you put on the stack will be the first one to resolve. (As a result, you can have those abilities resolve in the order of your choosing.)
• WWizards of the Coast2025-11-17
  Official Ruling
  A landfall ability triggers whenever a land you control enters for any reason. It triggers whenever you play a land, as well as whenever a spell or ability puts a land onto the battlefield under your control.
• WWizards of the Coast2025-11-17
  Official Ruling
  A landfall ability doesn't trigger if a permanent already on the battlefield becomes a land.

Rulings via Scryfall