edhseer Commander synergy, explained
Instant
Mana cost: {1}{U}
Counter target spell that's the second spell cast this turn.
on-cast —
Causes: counter a spell.
Cares about: nothing.
an instant is cast — 3,931 cards in the game can cause this (Second Guess is one).
When Second Guess 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 (Second Guess is one).
When Second Guess is cast:
5 other cards care about it too. These are the ones with the most connections.