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.

Ki Points (3).

FLURRY OF BLOWS
Immediately after you take the Attack action on your turn, you can spend 1 ki point to make two unarmed strikes as a bonus action.
PATIENT DEFENSE
You can spend 1 ki point to take the Dodge action as a bonus action on your turn.
STEP OF THE WIND
You can spend 1 ki point to take the Disengage or Dash action as a bonus action on your turn, and your jump distance is doubled for the turn.

Spellcasting. The xill battle-dancer is a 1st-level spellcaster. Its spellcasting ability is Charisma (spell save DC 12, +4 to hit with spell attacks). It has the following sorcerer spells prepared:

Cantrips (at will): blade ward, mage hand, mending, minor illusion

1st level (2 slots): expeditious retreat, [spell]shield[/shield]

Strength of the Grave. When damage reduces you to 0 hit points, you can make a Charisma saving throw (DC 5 + the damage taken). On a success, you instead drop to 1 hit point. You can’t use this feature if you are reduced to 0 hit points by radiant damage or by a critical hit.

After the saving throw succeeds, you can’t use this feature again until you finish a long rest.

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

Shortsword. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 8 (1d6 + 4) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d4 + 4) slashing damage. If 2 or more claw attacks hit, the target is grappled (escape DC 14). 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 13 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: +7 to hit, range 150/600 ft., one target. Hit: 8 (1d8 + 4) piercing damage.

Deflect Missiles. You can use your reaction to deflect or catch the missile when you are hit by a ranged weapon attack. When you do so, the damage you take from the attack is reduced by 1d10 + 7.
If you reduce the damage to 0, you can catch the missile if it is smalI enough for you to hold in one hand and you have at least one hand free. If you catch a missile in this way, you can spend 1 ki point to make a ranged attack with the weapon or piece of ammunition you just caught, as part of the same reaction. You make this attack with proficiency, regardless of your weapon proficiencies, and the missile counts as a monk weapon for the attack.