Callus

Callus is a face armor item that uses the StatusOnBattleEnd passive to stack permanent Shield on the wearer after each battle concludes. Over successive fights, the accumulated shield value grows, transforming a character who survives multiple encounters into an increasingly tanky juggernaut.

StatusOnBattleEnd means the trigger fires when combat ends, regardless of outcome, applying a shield buff that persists into the next fight. Because the Shield stacks are permanent rather than temporary, each battle completion compounds the previous total. Early in a run, Callus provides marginal benefit, but over time it becomes one of the most effective survivability items available — particularly for characters who can survive the early fragile phase.

Prioritize equipping Callus as early as possible to maximize stack accumulation across the run. It synergizes with any ability or item that scales off or interacts with Shield, turning the stacked buffer into a power multiplier. Effective on any class but especially valuable on frontline fighters who want to snowball survivability. The earlier you equip it and the more fights you survive, the more dominant it becomes by late-game.