Randomon (5e Creature)
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Large monstrosity, any chaotic alignment
Shield Shift. When the randomon is targeted by an attack roll, roll a d20. The result is added to the randomon's AC. The randomon's AC resets to 10 at the end of every creature's turn.
Unreliable Survivability. When the randomon makes a saving throw, ability check, or attack roll, roll an additional d10. The result is added to the d20 roll.
Immunity Change. At the start of each of the randomon's turn, roll two d12s. The result determines the randomon's condition and damage immunities for that turn. These immunities is lost at the beginning of the randomon's next turn.
Random Attack. Roll a d4. The randomon can make a number of random strikes or shots equal to the result.
Random Strike. Melee Weapon Attack: +d10 to hit, reach 5 ft., one target. Hit: Roll a d4 and multiply the result with a d6 roll. The attack deals that amount of damage. The type of damage is the same as the randomon's damage immunity for this turn.
Random Shot. Ranged Weapon Attack: +d10 to hit, reach 5d12 ft., one target. Hit: Roll a d4 and multiply the result with a d6 roll. The attack deals that amount of damage. The type of damage is the same as the randomon's damage immunity for this turn.
This deceptively dumb creature appears to often be a run-of-the-mill monstrous beast. However, it is known to sometimes appear in places of civilizations rather than crumbling dungeons, often as a disguised merchant or soothsayer of sorts. They speak mainly in riddles and are very capricious. It is nigh impossible to tell what runs through their mind or what they will do next. They are said to live for the thrill and do not fear luck whether good or bad.
Changing Armor. The randomon's armored body constantly adapts to new stimuli. It starts off initially rather soft. Whenever struck, the natural scales can shift into varying degrees of hardness. Normally, this would mean a randomon's defense can be impenetrable. However, due to their own whims, their armor hardness changes unpredictably. After one strike, it may turn hard as a diamond. In the next moment, it may have become as brittle as a bone. This tactic of unpredictable defenses extends to the randomon's adaptability, which makes it sometimes extremely hard to hit with even magic, and then completely clumsy in the next moment.