Obscurial (5e Creature)
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Medium humanoid (any race), chaotic evil
Saving Throws Wis +9, Cha +10
Obscurus Morph. When the obscurial's hit points drop below half its maximum total, the obscurial can turn into its obscurus form with no action on its part. It loses its humanoid type and becomes an aberration. The obscurial's AC becomes 18 (natural armor) and it gains truesight out to a range of 60 feet.
Innate Spellcasting. The obscurial is an 8th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 18, +10 to hit with spell attacks). The obscurial can innately cast the following spells, requiring no material components:
Cantrips (at will): fire bolt, light, prestidigitation
Maul (Obscurus Form Only). Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 35 (5d12 + 3) slashing damage.
Obscurials are powerful magic users forced to suppress their powers due to persecution. As a result of this suppression, their powers fester and grant them the ability to host the form of an obscurus. In this form, their suppressed power is unleashed and wreaks havoc with savage abandon. Even when not in obscurus form, however, obscurials are deadly spellcasters. Obscurials have a lot of pent-up rage and resentment which contributes to their chaotic and evil nature. However, those who show kindness to these creatures are known to live to tell the tale.