Your Eidolon represents your higher self. This Background measures how spiritual you are (note that "spiritual" does not necessarily mean "good"). Just as your Shadow tempts you toward Oblivion, your Eidolon gives you the resolve to fight the Shadow. Unlike your Shadow, your Eidolon does not communicate with you; it merely provides you with an additional bit of resolve against the Shadow.
For each dot you have in the Eidolon Background, you may add one additional die per session to any roll to resist the Shadow's powers, ploys or tricks, including Thorns. These dice may also be added to Willpower rolls.
It is a good idea to use your eidolon dice sparingly during a session, applying the extra dice only when absolutely necessary. You may choose to roll only one Eidolon die if yoy wish. Eidolon dice do not accumulate over several sessions, but you do regain your full total every game session.
You hear vague whispers from far away.
You know that there is something guiding you.
You feel that your Eidolon has a sentient identity.
You have sensed the presence of your Eidolon.
You have seen Eidolon in a dream.