edhseer Commander synergy, explained
Land — Mountain Plains
({T}: Add {R} or {W}.)
This land enters tapped unless you control two or more basic lands.
static —
Causes: nothing.
Cares about: nothing.
a Mountain enters the battlefield — 64 cards in the game can cause this (Radiant Summit is one).
When Radiant Summit enters:
a Plains enters the battlefield — 72 cards in the game can cause this (Radiant Summit is one).
When Radiant Summit enters:
a land enters the battlefield — 1,560 cards in the game can cause this (Radiant Summit is one).
When Radiant Summit enters:
199 other cards care about it too. These are the ones with the most connections.