edhseer Commander synergy, explained
Instant
Mana cost: {G}
As an additional cost to cast this spell, you may pay {2}{R}.
Prevent all combat damage that would be dealt this turn. If this spell's additional cost was paid, this effect doesn't affect combat damage that would be dealt by red creatures.
on-cast —
Causes: damage is prevented.
Cares about: nothing.
damage is prevented — 568 cards in the game can cause this (Undergrowth is one).
When Undergrowth has damage prevented:
an instant is cast — 3,931 cards in the game can cause this (Undergrowth is one).
When Undergrowth is cast:
427 other cards care about it too. These are the ones with the most connections.
anything is cast — 31,128 cards in the game can cause this (Undergrowth is one).
When Undergrowth is cast:
5 other cards care about it too. These are the ones with the most connections.