Chaos Monstrosity

Successive Explosion. When the chaos monstrosity is reduced to 0 hit points, reroll to get a new hit point maximum and use that value. Then roll a d8 to select an effect from the following list:

1. All creatures within a 20ft. radius take 2d6 fire damage, and the chaos monstrosity loses its fire immunity. 
2. All creatures within a 20ft. radius are blinded for 1 turn.
3. All creatures within a 20ft. radius are knocked prone, and the chaos monstrosity loses its lightning and thunder immunity. 
4. All creatures within a 20ft. radius take 2d6 cold damage, and the chaos monstrosity loses its cold immunity. 
5. The chaos monstrosity's speed is reduced to 10ft and they lose their swimming speed. 
6. All creatures within a 20ft. radius take 2d6 acid damage, and the chaos monstrosity loses its acid immunity. 
7. All creatures within a 20ft. radius take 2d6 bludgeoning damage, and the chaos monstrosity's armor class is reduced by 4.
8. The chaos monstrosity's subsequent max hit points are halved. 

Any effect with an area of effect can be avoided by succeeding on a DC 14 Dexterity saving throw. 

Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 7 (2d6) bludgeoning damage

Energy Blast. The chaos monstrosity launches a wave of elemental energy. Each creature within a 30ft. radius takes 16 (4d6 + 2) damage of a random type that the chaos monstrosity is immune to. If the chaos monstrosity has no damage immunities it cannot use this action.