Aggressive. As a bonus action, Atheaus can move up to its speed toward a hostile creature that it can see.
Hydra's Wrath: Atheaus deals an extra (1d8).fire damage when he hits with a weapon attack (included in the attacks)
Relentless Endurance. when Atheaus is reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. You can’t use this feature again until you finish a long rest.
Savage Attacks. When Atheaus score a critical hit with a melee weapon attack, you can roll one of the weapon’s damage dice one additional time and add it to the extra damage of the critical hit.
Volcano Born. Atheaus has resistance to fire damage. Atheaus is acclimated to high temps, because of his time spent living near the harshness of a active volcano Atheaus able to really withstand fire damage
Multi-attack. Atheaus makes two spear attacks and two Krytos' Kopis attack
Spear. Melee or Range Weapon attack +8 to hit 5ft reach or 20/60 ft, one target (1d6+4+1d8) piercing damage or (2d8+4) piercing damage if used with two hands
Krytos' Kopis: Melee Weapon attack +8 to hit 5ft reach (2d8+6) fire damage the blade glows with a dull heat like molten bronze, casting dim light and warmth for 15 feet
Arkadian Fire (3) This thick amber resin ignites when exposed to the air. As an action you can throw a ceramic jar of Arkadian fire up to 20 feet, shattering it on impact. Make a ranged attack against a creature or object, treating the ceramic jar as an improvised weapon. On a hit, the target takes 1d10 fire damage at the start of each of its turns. This lasts for 1d4 rounds or until the creature ends this damage by using its action to make a DC 10 Dexterity check to extinguish the flames. You can also pour a jar of Arkadian fire on the ground to cover a 5-foot-square area. The fire burns for 1d4 rounds and deals 1d10 fire damage to any creature that enters the area or ends its turn in the area. A creature can take this damage only once per turn.
Hydra's Rebuke (3 a day). As a reaction to being damaged by a creature within 30 feet, Atheaus may blast the creature that damaged him with crackling flames. The creature must make a Dc 18 dexterity saving throw. It takes (4d10+10) fire damage on a failed save, or half as much damage on a successful one