Voidling

Fed by Darkness. A voidling in magical darkness at the start of its turn heals 5 hit points.

Magic Resistance. The voidling has advantage on saving throws against spells and other magical effects except those that cause radiant damage.

Innate Spellcasting. the voidling's innate spellcasting ability is Wisdom (spell save DC 15, spell attack bonus +7). It can innately cast the following spells, requiring no material components: at will: darkness, detect magic, fear 3/day each: eldritch blast (3 beams), black tentacles 1/day each: phantasmal force, reverse gravity

Natural Invisibility. A voidling in complete darkness is considered invisible to creatures that rely on normal vision or darkvision.

Multiattack. The voidling makes 4 tendril attacks.

Tendril. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 10 (1d8 + 6) slashing damage plus 11 (2d10) necrotic damage.

Necrotic Burst (Recharge 5-6). The voidling releases a burst of necrotic energy in a 20-foot radius sphere centered on itself. Those in the area take 35 (10d6) necrotic damage, or half damage with a successful DC 17 Constitution saving throw.