Awakened Fireball

Hot Stuff. Creatures that end their turn within 5 ft of the awakened fireball take 5 (1d10) fire damage.

Illumination. The elemental sheds bright light in a 30-foot radius and dim light in an additional 30 feet.

Water > Fire. For every gallon of water that the awakened fireball comes into contact with, it takes 5 cold damage.

Goodbye cruel world. When the fireball is reduced below 10 hit points, it can detonate. Casting Fireball 8d6 centred on itself. 

The casting ability for this creature is Dexterity for this creatures spells and abilities. If the Awakened Fireball subjects a creature to a saving throw, the spell save DC is 14.

Touch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Detonation. When the fireball is reduced to 0 hit points, it can detonate. Casting Fireball 8d6 centred on itself.