edhseer Commander synergy, explained
Land
This land enters tapped.
Add {W} or {B}.
activated {T} — adds 1 mana
Until end of turn, this land becomes a 2/3 white and black Elemental creature with lifelink. It's still a land.
activated {1}{W}{B} — turns something into a creature
Causes: nothing.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Shambling Vent is one).
When Shambling Vent enters:
199 other cards care about it too. These are the ones with the most connections.