Fire Absorption. Whenever the fusiliex is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.

Immutable Form. The fusiliex has advantage on saving throws against any spell or effect that would alter its form.

Magic Resistance. The fusiliex has advantage on saving throws against spells and other magical effects.

Magic Weapons. The fusiliex's weapon attacks are magical.

Molten Heat. Whenever a creature ends its turn within 5 feet of the fusiliex (including the fusiliex itself), that creature must make a DC 19 Constitution saving throw or take 7 (2d6) fire damage. If they are wearing or carrying a metal object, they have disadvantage on this saving throw and must drop the object if they are carrying it if they fail the saving throw. The fusiliex fails the saving throw automatically, but doesn't suffer any adverse effect other than the fire damage.

Illumination. The fusiliex sheds bright light in a 30-foot radius and dim light in an additional 30 feet.

Multiattack. The fusiliex makes two melee attacks.

Slam. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 20 (3d8 + 7) bludgeoning damage. The target must then make a Constitution saving throw or take 5 (1d10) fire damage on a failed save.

Sword. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 23 (3d10 + 7) slashing damage.

Arderic Eruption (Recharge 6). The fusiliex releases fiery exhaust in a 20-foot cone. Each creature (including itself) in that area must make a DC 19 Dexterity saving throw, taking 45 (10d8) fire damage on a failed save, or half as much damage on a successful one. THe fusiliex automatically fails this saving throw.