The Abnormal tier is split into two sub-tiers: Combat Abnormal and Utility Abnormal.
Combat Abnormal Mobs
Despite Bairns, Scampers, and Gastgebers being classified as Combat Abnormal, their entity class actually extends them to the Infected and Evolved tiers respectively (Bairns as Infected and Scampers and Gastgebers as Evolved).
Shared Aspects & Capabilities
Abnormal are hostile (excluding Gastgebers) to most non-Spore mobs, with the exceptions being Animals and Fish (unless Should attack Animals is enabled via the Config) and mobs included in the Mobs Not Targeted blacklist within the Config.
Can perform short dashes in liquids to pursue a target.
Able to utilize Kill Points to grant themselves buffs.
Present a weakness to the cold.
Utility Abnormal Mobs
Trivia
The Abnormal tier is also called 'Unknown' and 'Anomalies' due to the nature of the Mobs.
Calamity Limbs are referred to as 'FallenMultipartEntities' in the code.