Butterfly Drake Guardian

Hypnotic Flutter. Hypnotic Flutter causes target to make a WIS saving throw DC 15 or be charmed. Player can roll another con save at the beginning of the next turn

Spellcasting. The Butterfly Drake Guardian is a 9th level spellcaster. Its spellcasting ability is Intelligence (spell save DC 15, + 5 to hit with spell attacks). 

Cantrips (at will): Poison Spray (Con DC 15 failed save = 2d12 poison damage),  Infestation (Con DC 12 failed save = swarmed by poisonous butterflies take 1d6 poison damage and pushed 5ft in a direction)

Spells (2 slots): Hallucinatory Terrain (1 slot, makes a natural terrain in a 150ft cube to look, sound, and smell like some other sort of terrain. individuals must make a investigation check DC 15 to notice the illusion),  Entangle (1 slot, in a 20 ft square weeds and vines sprout up tangling someone within them individuals ensnared must make strength check against spell DC 15 to free itself)

Multi-attack. The butterfly drake guardian makes two attacks one with bite one with tail.

Bite. Melee Weapon Attack: Reach: 5 ft., one target. Hit: +7 (1d8 + 3) piercing damage. 

Tail Thorns. Ranged Weapon Attack:  Range:  10ft./30 ft.  (2d10 + 2) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5ft., one target (2d6 +2) slashing damage

Hide, and Dodge

Thunderous Yelp. As a reaction this creature can cry out causing deafness (to those who fail a CON save DC of 15) until their next turn.

When the Butterfly Drake Guardian feels cornered or severely threatened its likely to use its Legendary Action to protect itself just make sure you're not the closest.

Venomous Sting (Recharge 6).  during combat the drake can sting the creature closest to it requiring a DC 17 CON save, on failure the target becomes paralyzed. at the beginning of the targets turns they may make another save and remain paralyzed until success