Sigil of the Dead

Sigil of the Dead is a Keepsake that increases Zagreus' default God Gauge percentage at the start of an encounter, and allows Zagreus to access the Hades' Aid Call. It is obtained by giving Hades two gifts of Nectar in the House of Hades. Its effects can be enhanced by clearing enough encounters with the keepsake equipped.

Unequipping the Sigil of the Dead between levels removes Zagreus' access to Hades' Aid and the bonus to God Gauge fill at the start of encounters.

Effects
Your Call becomes Hades' Aid, which briefly makes you Invisible; your God Gauge starts full.

Bond Message
From Hades; you share an Intractable Bond

The feared and distant Underworld King knows that his hardest work is still ahead of him.