Bomb

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

Water Susceptibility. For every 5 feet the elemental moves in water, or for every gallon of water splashed on it, it takes 1 cold damage. This damage will also cause the threat state to revert to the next lower level.

Touch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) fire damage.

If in stage 2 or 3, this instead deals 14 (2d6 + 1d8 + 3) 

Self-Destruct. DC 18 Dex save . After the bomb has reached the third threat state, if the bomb has not been doused in water or killed outright, the bomb will explode dealing 54 (12d8) fire damage and 20 (3d12) bludgeoning damage to all creatures within 10 feet.

Upon taking damage for the first time in a round, the bomb will use its reaction to change into one of these threat states:

1. The bomb will increase slightly in size and will shed more light, bright light out to 40 ft and dim light for an additional 40ft.

2. The bomb will increase in size again, and begin to glow white hot. Fire damage it deals in this state is increased by 1d8.

3. The bomb will enter its final stage, and begin hissing as though a fuse has been lit. The bomb will self-destruct at the start of its turn.