Archon, Ursan 2014
CR 9 celestial
Large celestial, chaotic good
Its weapon attacks are magical. When it hits with any weapon deals an extra 4d8 force (included below).
Doesn't require food drink or sleep
Advantage: spell/magic effect saves.
At the start of its turn can gain advantage on all melee weapon attack rolls it makes during that turn but attacks vs. it have advantage until start of its next turn.
If it takes 30 damage or less that would reduce it to 0 hp it is reduced to 1 hp instead.
Reactions
When it reduces a creature to 0 hp it can utter a triumphant roar. Each friendly creature within 60' of the archon that is frightened paralyzed stunned or unconscious has advantage on its next save. A friendly creature with o those conditions has advantage on its next attack roll. In addition each friendly creature within 60' of archon that can hear the roar gains 14 (4d6) temp hp.
Source: Tome of Beasts 3 (Kobold Press) · License: OPEN GAME LICENSE Version 1.0a details