edhseer Commander synergy, explained
Land
This land enters tapped.
Add {B}.
activated {T} — adds 1 mana
This land becomes a 1/1 black Skeleton creature with that ability until end of turn. It's still a land.
activated {1}{B} — turns something into a creature
Regenerate this creature
activated {B} —
Causes: regenerate a creature.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Spawning Pool is one).
When Spawning Pool enters:
199 other cards care about it too. These are the ones with the most connections.