Charjabug (5e Creature)
From D&D Wiki
Small monstrosity, any alignment
Battery. All creatures of the charjabug's choice within 30 feet of it have advantage on spell attack rolls.
Spark. Ranged Spell Attack: +5 to hit, range 20/60 ft., one target. Hit: 7 (1d8 + 3) lightning damage.
Arc Bolt. When a creature hits the charjabug with a melee attack, it can use its reaction to deal 4 (1d8) lightning damage to the attacker.