edhseer Commander synergy, explained
Land
As this land enters, you may reveal a Mountain or Forest card from your hand. If you don't, this land enters tapped.
Add {R} or {G}.
activated {T} — adds 1 mana
Causes: nothing.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Game Trail is one).
When Game Trail enters:
199 other cards care about it too. These are the ones with the most connections.