edhseer Commander synergy, explained
Land
Choose a color. Add one mana of that color unless any player pays {1}. Activate only as an instant.
activated {T} — adds 1 mana
Causes: nothing.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Rhystic Cave is one).
When Rhystic Cave enters:
199 other cards care about it too. These are the ones with the most connections.