edhseer Commander synergy, explained
Land
This land enters tapped unless you control a planeswalker.
Add {W} or {U}.
activated {T} — adds 1 mana
Causes: nothing.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Fatehold Annex is one).
When Fatehold Annex enters:
199 other cards care about it too. These are the ones with the most connections.