Corrupted automata

Chaos orb core. If a corrupted automata is brought down to exactly 1 hp, then the chaos orb implanted in its core is damaged and the automata turns into a Chaos Construct

Corruption. If a corrupted automata brings a construct to 0 hp, the construct is animated as a Corrupted Automata for 1d4 days unless a corrupted Chaos Core is inserted into the construct, which renders the effect permanent.

Fortitude. At the beginning of an encounter with one or more Corrupted Automata, roll 1d20 for each Corrupted Automata present. if an Automata gets a 20, each time they are reduced to 0 HP from any source other than lightning damage, the automata makes a constitution saving throw. The DC is either 10 or half the damage taken, on a success the Automata instead drops to 1 HP, triggering the Chaos or core ability.

Multiattack. An automata can make 2 slams or a chaotic discharge (if available)

Weapon. Melee Weapon Attack: +5 to hit, reach 5 or 10 ft. Hit: 5 (1d6 + 2) bludgeoning damage damage.

Chaotic discharge (recharge on 6). Ranged Weapon Attack: +4 to hit, range 30 ft cone. Hit: 6 (1d10 + 1) random damage.

Pistons. The corrupted automata can change it's melee range from 5 feet to 10 feet, although doing so makes it unable to attack things creatures within 5 feet of it until it uses a bonus action to retract the pistons returning its range to 5 feet.