Actions

Multiattack.

The thri-kreen makes two Gythka attacks or four Psychic Bolt attacks.

Gythka.

Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 10 (2d8 + 1) slashing damage.

Psychic Bolt.

Ranged Spell Attack: +6 to hit, range 60 ft., one creature. Hit: 6 (1d6 + 3) psychic damage.

Drain Vitality (Recharges after a Short or Long Rest).

The thri-kreen targets one creature it can see within 30 feet of itself. The target must make a DC 14 Constitution saving throw, taking 32 (5d12) necrotic damage on a failed save, or half as much damage on a successful one. The thri-kreen regains hit points equal to the damage dealt.

Spellcasting (Psionics).

The thri-kreen casts one of the following spells, requiring no spell components and using Wisdom as the spellcasting ability:

At will: levitate (self only), mage hand (the hand is invisible)
1/day each: freedom of movement (self only), invisibility (self only)

Bonus Actions

Chameleon Carapace.

The thri-kreen changes the color of its carapace to match the color and texture of its surroundings, gaining advantage on Dexterity (Stealth) checks it makes to hide in those surroundings.

Thri-kreen Mystic