Leprechaun

Magical Resistance. The Leprechaun has advantage on Saving Throws against spells and other magical effects.

Magic Weapons. The Leprechaun's weapon attacks are magical.

Spellcasting. The Leprechaun is a 9th level spellcaster. Its spellcasting ability is charisma (spell save DC 16, +8 to hit with spell attacks). The leprechaun has following spells prepared:
Cantrips (at will): Mage Hand, Prestidigitation, Minor Illusion
1st level (3 slots): Charm Person, Color Spray, Sleep
2nd level (3 slots): Invisibility, Mirror Image, Spider Climb
3rd level (2 slots): Clairvoyance, Hypnotic Pattern
4th level (2 slots): Locate Creature, Polymorph
5th level (1 slots): Animate Objects, Dominate Person

Wish. If the leprechaun finds itself in a situation where it needs something from someone that it cannot acquire itself (ie, it is captured), it may bargain using the Wish spell. The Leprechaun may grant up to 3 wishes to whomever it desires once per day. After the finalienable qish is granted, it will offer a another. If the extra wish is accepted and made, the others are undone. Almost always, the outcomes of the wishes are not what was originally desired as the mischievous nature of the leprechaun finds a way to alter the result. 

Pot of Gold. At will, the leprechaun can summon his pot of gold from the ethereal plane and send it back just the same. Any character who takes an item from the Pot without the approval of the leprechaun is considered cursed and cannot taste, smell, or feel warmth until the curse is broken or lifted. Any perception check made with those senses is an automatic failure. While cursed, the leprechaun can detect the general location of the individual as a bonus action as long as they reside on the same plane.  

Multiattack. The Leprechaun makes two melee attacks.

Knotted Cane. Melee Weapon Attack: +10 to hit, reach 5 ft. one target. Hit: 13 (1d8 + 9).