Holiness

Version 0.30: This article may not be up to date for the latest stable release of Crawl.

All monsters in Crawl are sorted into six fundamental categories of holiness: Holy, Demonic, Undead, Non-living, Plant, and Natural.

Monsters of each type of holiness have several attributes in common. For instance, all plants, undead, and nonliving are unbreathing. Only natural or plant monsters are vulnerable to negative energy. Demons and undead are automatically evil.

From mon-data.h:37 (0.30.0):

MH_HOLY       - irritates some gods when killed, immunity from holy wrath weapons. Includes good priests.
MH_NATURAL    - baseline monster type
MH_UNDEAD     - immunity from draining, pain, torment; resistance to poison; extra damage from holy wrath
MH_DEMONIC    - similar to undead, but no poison resistance, *no* automatic damnation resistance
MH_NONLIVING  - golems and other constructs
MH_PLANT      - plants