Hi.

Mistveil Defenders (2 existing IDs https://www.wowhead.com/npc=163058/mistveil-defender -- https://www.wowhead.com/npc=171772/mistveil-defender ) can cast an enrage at around 25% (see this log for exemple https://www.warcraftlogs.com/reports/KkjWXx27J4DqbpAZ?fight=1&type=auras&hostility=1&source=25.2&ability=324737&view=events )

Enraged spell : https://www.wowhead.com/spell=324737/enraged

From my experience, only the very first 2 Defenders of the maze possess this ability. The other Defenders do not.