Elemental Affinity. When Koth casts a spell that deals fire damage, he can add his Charisma modifier (+3) to one damage roll of that spell. 

Spellcasting. Koth is a 7th level spellcaster. His spellcasting ability is Charisma (spell save DC 14, +6 to hit with spell attacks). He has following sorcerer spells prepared:

Cantrips (at will): chill touch, fire bolt, mage hand, minor illusion, prestidigitation

1st level (4 slots): ray of sickness, charm person, shield

2nd level (3 slots): blur, hold person

3rd level (3 slots): counterspell, fireball, 

4th level (1 slots): wall of fire

Twinned Spell (recharge 4-6). When you cast a spell that targets only one creature and doesn’t have a range of self, you can target a second creature in range with the same spell.

Arcane Advantage. Once per turn, the hobgoblin can deal an extra 7 (2d6) damage to a creature it hits with a damaging spell attack if that target is within 5 feet of an ally of the hobgoblin and that ally isn’t incapacitated.

Army Arcana. When the hobgoblin casts a spell that causes damage or that forces other creatures to make a saving throw, it can choose itself and any number of allies to be immune to the damage caused by the spell and to succeed on the required saving throw.

Morningstar. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) piercing damage.

Wand of Magic Missiles (7 charges).For one charge, casts the 1st-level version of the magic missile spell; increase the spell slot level by one for each additional charge expended. The wand regains 1d6+1 expended charges daily at dawn. If Koth expends the wand's last charge, roll a d20. On a 1, the wand crumbles into ashes and is destroyed.

Potion of Flying. When Koth drinks this potion, he gains a flying speed equal to his walking speed for 1 hour and can hover. If he's in the air when the potion wears off, he falls unless he has some other means of staying aloft.