Besides (one presumes) their kidnapped victims, bugbears subsist on such inedible provender as glass shards, potash, and the heads of rabid bats. They consider certain venomous toads an utter delicacy.
Azurthite bugbears are statted like regular 5e bugbears with the following differences:
Skills Stealth +6
Plastic. Bugbears can squeeze through spaces as small as 1 inch.
Shadow Stealth. While in dim light or darkness, a bugbear can hide as a bonus action.
Sunlight Weakness. In bright sunight, bugbears have a disadvantage to attack rolls, ability checks, and saving throws.