Aethers Sight. Magical darkness doesn't impede the Xelorl's darkvision.

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

Aether Deflection.  The Xelor takes half damage from all physical attacks.

Multiattack. The devil makes two melee attacks: two with its Xelor blade or two with its Xelor bow.  It can use Hurl Aether in place of any melee attack.

Xelor Blade. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9(1d8 + 3) slashing damage.

Xelor Bow. Ranged Weapon Attack: +6 to hit, range 200 ft., one target. Hit: 9 (1d8 + 3) piercing damage. 

Hurl Aether. Ranged Spell Attack: +6 to hit, range 150 ft., one target. Hit: 14 (4d6) radiant/necrotic damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 17 Constitution saving throw or lose 10 (3d6) hit points at the start of each of its turns due to an Aetherial wound. Each time the Xelor hits the wounded target with this attack, the damage dealt by the wound increases by 10 (3d6). Any creature can take an action to stanch the wound with a successful DC 12 Inteligence (arcana) check. The wound also closes if the target receives magical healing.