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

Ethereal Jaunt. As a bonus action, the xill can magically shift from the Material Plane to the Ethereal Plane, or vice versa.

Multi attack. The xill makes four attack which can be any combination of claws and short sword attack or make two long bow attacks and if all attacks hit it can make a bite attacks. 

Claw. Melee Weapon Attack: +4 to hit, reach 5 ft., 1 target. Hit: 4 (1d4 + 2) slashing damage and if the xill hits with at least two claws it grapples the target and whilst grappling that target can automatically hit it with two claw attacks. 

Short sword. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 6 (1d6 + 3) slashing damage. 

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., 1 target. Hit: 6 (2d4 + 2) piercing damage and the target must make a dc 13 constitution saving throw or be paralyzed for 1 minute, On a failed save the target can remake the save at the end of their turn. 

Long bow. RangedWeapon Attack: +5 to hit, range 40/360 ft., 1 target. Hit: 7 (1d8 + 3) piercing damage.