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