Astral Goose

Distinguished. Upon being spotted by a creature with at least 4 intelligence, they must succeed on a DC 15 Wisdom saving throw or become charmed/frightened (coin flip) for 1 minute. This effect only applies once per creature per day.

Chaotic Mind. The Astral Goose is immune to scrying, and any effect that would detect its location. Any attempts to read its thoughts or sense its emotions triggers The Honking reaction.

Disarm. On a successful Bite attack, roll Sleight of Hand against the target's Str/Dex saving throws to remove one object from the target's hands (weapons, shields, etc). The Astral Goose may immediately drop the item, or carry it with them. If they choose to carry it they cannot Bite or Honk until it is dropped.

Psionic Spellcasting. The Astral Goose is a 5th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 15, +7 to hit with spell attacks). The Astral Goose has following spells prepared:
Cantrips (at will): Honk
1st level (4 slots): Vicious Honkery
2nd level (3 slots): Locate Object, Pass without Trace
3rd level (2 slots): Major Image, Astral Gate

Multiattack. The Astral Goose may make a Bite attack as a bonus action.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 14 (2d8 + 5) piercing damage. 

Honk. Ranged Spell Attack: +7 to hit, range 30 ft., sphere. Hit: 12 (2d8 + 3) thunder  damage.

Vicious Honkery. Ranged Spell Attack: +7 to hit, range 60 ft., up to 7 targets. Hit: 14 (2d10 + 3) psychic damage and impose disadvantage on the next attack roll the target makes in the next turn.

Astral Gate. The Astral Goose can transport themselves and up to 8 adjacent willing creatures or objects they choose to their home in the astral plane. Alternatively the Astral Goose may bring the same number of creatures or objects from the Astral Plane to a location of their choosing on the material plane (Roll 1d100: 01-05 similar area, 06-25 off target by 5d8 kilometers or 5d5 miles, 26-100 on target)

The Honking. Unless the Astral Goose otherwises chooses, their mind is in a constant deafening state of honking. Anyone else who hears this needs to roll a DC 15 Charisma save taking 14 (2d10 + 3) psychic damage on a failure, or half as much on a success.

The Astral Goose can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Astral Goose regains spent legendary actions when they successfully steal an item with Disarm.

Escape Teleport. The Astral Goose can teleport up to 120 ft to somewhere it can see or has seen previously with no chance of error.

Invisibility. (Costs 2 actions) The Astral Goose becomes invisible until the end of their next turn.