Xenoc of the Underworld

Blaze. Xenoc emits a 5 ft fiery aura. Any creature that starts their turn within the aura must succeed on a DC 14 Consitution saving throw or take 1d4 fire damage.

Spellcasting. Xenoc is a 3rd-level spellcaster. Its spellcasting ability is charisma (spell save DC 14, +3 to hit with spell attacks). Xenoc has following warlock spells prepared:
Cantrips (at will): Eldritch Blast,  Blade Ward, Booming Blade, Green Flame Blade
1st level (4 slots): Witch Bolt, Hex                                                                                                      2nd level (3 slots): Misty Step, Mirror Image                                                                                    3rd level (2 slots): Counterspell, Fear, Vampiric Touch.

Demonic Blade. Xenoc can cast a cantrip after landing a malee weapon or spell attack. This effect can only activate once per turn.

Flaming Aspect. When Xenoc makes a malee weapon attack the damage can be either slashing or fire damage.

Helo Slash. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit:  10 (1d10 ) Slashing damage.