edhseer Commander synergy, explained
Land
As this land enters, choose a creature type.
Add {C}.
activated {T} — adds 1 mana
Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.
activated {T} — adds 1 mana
Causes: nothing.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Secluded Courtyard is one).
When Secluded Courtyard enters:
199 other cards care about it too. These are the ones with the most connections.