Stealth

Stealth is an enemy only status effect in Darkest Dungeon that prevents monsters from being targeted. Generally, it will only last for the first two rounds, though there may be some exceptions. Enemies that have Stealth can still be hit by attacks that hit multiple targets and the Arbalest's Blindfire. Additionally, some hero skills can bypass Stealth and can target enemies with it. If an enemy is hit with such a skill, they will no long have Stealth.

It is signalled by a purple eye icon and monsters are a murky grey-blue while they have Stealth.

Enemies with Stealth
Enemies will only have stealth in Veteran and above missions.