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.
Your Call becomes Hades' Aid, which briefly makes you Invisible; your God Gauge starts 10/20/30% full.
From Hades; you share an Intractable Bond
The feared and distant Underworld King knows that his hardest work is still ahead of him.
- The Sigil of the Dead cannot be equipped in the middle of an escape attempt if another god's Aid has been chosen.
- While Invisible, Zagreus cannot be targeted, moves faster, and deals bonus damage for 2 seconds (or until he strikes).
- At Max Gauge, Zagreus turns Unseen instead of Invisible.
- While Unseen, Zagreus cannot be targeted, moves faster, and deals bonus damage for 5 seconds, the bonus not being lost when Zagreus strikes.
- Activating the Call while under the effects of Styx Poison removes the effect. It also removes Hades' Skull Casts from the ground, but not the Boiling Blood debuff when hit.
- The Sigil is one of two Keepsakes that can only be acquired after finishing the main story, the other being the Pom Blossom.
- The Sigil is a secret Keepsake, and does not have a corresponding locked space in the Keepsake Collection. When unlocked, it occupies the blank space next to the Pom Blossom.
- A few amusing interactions play out when Zagreus uses Greater Call against his own father.