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

Implant. A xill can lay eggs inside a paralyzed creature. The young emerge 7d10 days after infection, devouring the host from the inside. A remove disease spell rids the victim of the egg. Performing a DC 20 Wisdom (Medicine) check also gets rid of an egg. If the check fails, the healer can attempt the check again. Each further attempt, whether it was successful or not, deals 1d6 poison damage to the target.

Planewalk. Xill slip between the etheral plane and the material plane to attack enemies as though from thin air. As a bonus action, they can cross from the ethereal to any touching plane. If a target was unaware of the xill’s location prior to being attacked, the attacks of that round are with advantage. To move back to the ethereal, the transfer happens at the start of their next turn. They are immobile from the time they start the Planewalk until they finish the next round as they phase out. Their physical bodies start leaving their current plane as soon as the ability is activated, causing those who attack them to attack with disadvantage. A xill can planewalk with one willing or incapacitated creature. They must maintain concentration during the Planewalk. If concentration is broken, they must start over.

Second Wind. On its turn, the xill warrior can use a bonus action to regain hit points equal to 1d10 + 4.

Action Surge. On its turn, the xill warrior can take one additional action on top of its regular action and a possible bonus action.

Improved Critical. The xill warrior’s attacks score a critical hit on a roll of 19 or 20.

Multiattack. The xill attacks with 4 claws, 2 claws and 2 short swords, or 2 long bow attacks.

Shortsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 7 (1d6 + 3) piercing damage.

Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d4 + 3) slashing damage. If 2 or more claw attacks hit, the target is grappled (escape DC 12). If more than 2 claws hit, the target gets disadvantage on it’s check to escape the grapple.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one grappled target. Hit: 8 (2d4 + 3) piercing damage and the target must make a DC 14 Constitution saving throw or become poisoned for 1 hour. While poisoned in this way, the target is also paralyzed. As a bonus action, the xill can Implant against a paralyzed target. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Longbow. Ranged Weapon Attack: +6 to hit, range 150/600 ft., one target. Hit: 7 (1d8 + 3) piercing damage.