Booyahg Slave of the Fiend

When the goblin makes an ability check or saving throw, it can add a d10 to the roll. It can do this after the roll is made but before any of the roll's effects occur.

The goblin's innate spellcasting ability is Charisma. It can innately cast the following spells (spell save DC 15), requiring no material components:

At will: alter self, false life, levitate (self only), mage armor (self only), silent image

1/day each: feeblemind, finger of death, plane shift

The goblin is a 17th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 15, +7 to hit with spell attacks). It regains its expended spell slots when it finishes a short or long rest. It knows the following warlock spells:

Cantrips (at will): eldritch blast, fire bolt, friends, mage hand, minor illusion, prestidigitation, shocking grasp

Level 5 (4 slots): banishment, burning hands, flame strike, hellish rebuke, magic circle, scorching ray, scrying, stinking cloud, suggestion, wall of fire

Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 3 (1d6) bludgeoning damage plus 10 (3d6) fire damage.