Cadmus, Cursed Boar of Ares

Relentless (Recharges after a Short or Long Rest). If Cadmus takes 27 damage or less that would reduce it to 0 hit points, it is reduced to 1 hit point instead.

Spirit of War (Mythic Trait; Recharges after Short or Long Rest). If Cadmus is reduced to 0 hit points, he doesn't die or fall unconscious. Instead, the flesh of his body burns away, regains 73 hit points. In addition he has a fiery aura of 10ft. When a creature moves into or within the area at the start of their turn, it takes 3  (1d6) fire damage. Any flammable objects in the aura will combust into flame.

Multiattack. Cadmus makes two melee attacks: one with its fire tusks and one with its fire hooves.

Fire Tusks. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (2d6 + 5) slashing damage plus 7 (2d6) damage.

Fire Hooves. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage plus 7 (2d6) damage. 

Fire Ball (Recharge 6). Cadmus shoots a fire ball at one creature it can see within 120 feet of it. The target must make a DC 15 Dexterity saving throw, taking 18 (4d8) fire damage on a failed save, or half as much damage on a successful one.

If Cadmus' mythic trait is active, it can use the options below as mythic actions for 1 hour after using Spirit of War. Cadmus can take 3 Mythic actions. Only one Mythic action option can be used at a time and only at the end of another creature’s turn. Cadmus regains spent Mythic actions at the start of its turn.

Rampage. Cadmus makes two attacks: one with his tusks and one with his hooves.

Destruction. (Costs 2 actions). Each creature within 15 feet of Cadmus must make a DC 16 Dexterity saving throw, taking 13 (3d8) fire damage on a failed save, or half as much damage on a successful one. Until the start of its next turn, Cadmus gains a +2 bonus to AC.