edhseer Commander synergy, explained
Enchantment
Mana cost: {R}{R}
Whenever one or more creatures you control attack, each defending player divides all creatures without flying they control into a "left" pile and a "right" pile. Then, for each attacking creature you control, choose "left" or "right." That creature can't be blocked this combat except by creatures with flying and creatures in a pile with the chosen label.
triggered —
Causes: nothing.
Cares about: a creature attacks.
an enchantment is cast — 3,673 cards in the game can cause this (Raging River is one).
When Raging River is cast:
255 other cards care about it too. These are the ones with the most connections.
a nontoken enchantment enters the battlefield — 3,691 cards in the game can cause this (Raging River is one).
an enchantment enters the battlefield — 3,743 cards in the game can cause this (Raging River is one).
When Raging River enters:
59 other cards care about it too. These are the ones with the most connections.