Arcane Signet
Artifact
: Add one mana of any color in your commander's color identity.
Isilu's adherents invoke its blessings with contemplation at sites marked by standing stones. Where there is quiet, there is the moon's inspiration.
Illustrated by
Lorwyn Eclipsed Commander#56UncommonEnglishLegality
Rulings
Nov 10, 2020
If you have two commanders, the ability adds one mana of any color in their combined color identities.
Nov 10, 2020
If your commander is a card that has no colors in its color identity, Arcane Signet's ability produces no mana. It doesn't produce 
.
Nov 10, 2020
If you don't have a commander, Arcane Signet's ability produces no mana.