Shattered Shackle is a Keepsake that increases the damage dealt by Zagreus' Attack, Special and Cast when they are not empowered by a Boon. It is obtained by giving Sisyphus a gift of Nectar when he is found in the dungeon. Its effects can be enhanced by clearing enough encounters with the keepsake equipped.
Unequipping the Shattered Shackle between levels will remove the damage bonus to abilities not enhanced by a Boon.
Your Attack, Special, and Cast each deal +50/75/100% damage while not empowered by a Boon.
From Sisyphus; you share a Rock-Solid Bond
If he can hoist a boulder on his own, he knows he can be of some support.
- In order for the Shackle's bonuses to work, no Boons must be equipped in the Attack, Special or Cast slots. Chaos boons, Daedalus weapon upgrades and Hermes boons do not affect the bonuses you get from the Shackle, nor do defensive boons, dash boons or miscellaneous boons from gods. In addition, assignment of a boon to a given slot does not void the bonus from the other slots (so for example, if you're forced to take a Cast boon, it does not affect Attack and Special).
- The Shattered Shackle went through a rework - its first effect was falling rubble from pillars and traps dealing more damage to enemies.