Nester

Nester has advantage on saving throws against spells and other magical effects.

Nester is an 18th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). Nester can cast disguise self and invisibility at will and has the following wizard spells prepared:

• At will: disguise self, invisibility.

• Cantrips (at will): fire bolt, light, mage hand, prestidigitation, shocking grasp
• 1st level (4 slots): detect magic, identify, mage armor*, magic missile
• 2nd level (3 slots): detect thoughts, mirror image, misty step
• 3rd level (3 slots): counterspell, animate dead, lightning bolt
• 4th level (3 slots): blight, fire shield, stoneskin*
• 5th level (3 slots): cone of cold, Rary's telepathic bond, wall of force
• 6th level (1 slots): globe of invulnerability
• 7th level (1 slots): teleport
• 8th level (1 slots): mind blank*
• 9th level (1 slots): time stop

*Nester casts these spells on itself before combat.

Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 4 (1d4 + 2) piercing damage.

Any spellcaster that can cast the find familiar spell (such as an archmage or mage) is likely to have a familiar. The familiar can be one of the creatures described in the spell (see the Player's Handbook) or some other Tiny monster, such as a crawling claw, imp, pseudodragon, or quasit.