edhseer Commander synergy, explained
Instant
Mana cost: {B}
Until end of turn, lands you control gain "Sacrifice this land: Add {B}."
on-cast — grants a keyword
Causes: nothing.
Cares about: nothing.
an instant is cast — 3,931 cards in the game can cause this (Rain of Filth is one).
When Rain of Filth 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 (Rain of Filth is one).
When Rain of Filth is cast:
5 other cards care about it too. These are the ones with the most connections.