Cacophony

Quadrupedal Balance. Cacophony walks upon four great, metal legs beneath its upright body.  It has advantage on savings throws against any ability that may cause the prone condition.

Siege Construct. Cacophony does double damage to structures.

Static Cling. Cacophony's form is prone to the retention of lightning based power due to the interaction between its magical empowerment and the metal it is built from. Any Lightning damage done to it will linger, up to a total of 60 points.  Once an amount of Lightning damage equal to or exceeding 60 is done in total, Cacophony will use its Calamitous Release reaction.

Multiattack. Cacophony makes three attacks using any combination of its Crushing Cymbals and Shrieking Strings.

Crushing Cymbal. Melee Attack: +12 to hit, reach 15 ft, one target. Hit: 18 (2d8 + 9) Bludgeoning damage. A medium or smaller creature hit by this attack must make a DC 15 Strength saving throw or be knocked 10 ft. away from Cacophony.  A creature that fails this saving throw by 10 or more is knocked prone instead.

Shrieking Strings. Ranged Attack: +10 to hit, 60 ft. range, one target. Hit: 13 (2d6 + 6) thunder damage. On a critical strike, Cacophony deals an additional 1d6 Psychic damage.

Catastrophe Calliope. (Recharge 5-6). Cacophony emits a massive burst of sound from every instrument on its form.  Every creature within 60 ft. must make a DC 17 Constitution saving throw, taking 28 (5d10) thunder damage and becoming deafened on a failed save.  A creatures that succeeded on its saving throw takes half damage and is not deafened.  Any creature that fails it's saving throw by 10 or more is also stunned for one round.  A creature may make DC 15 Constitution save at the end of it's turn, ending the deafened condition on a success.

Calamitous Release. This reaction can only be used if Cacophony has suffered a total of 60 lightning damage. It will use its reaction to discharge the accumulated power, reducing the amount of lingering Lightning damage to zero.  Roll 1d6.

1-2 Reversed Crescendo: Cacophony takes 60 Lightning damage.
3 Disastrous Din: Cacophony takes 60 lightning damage and each creature within 10 feet of it must make a DC 15 Dexterity saving throw, taking 60 lightning damage on a failure, half as much on a success.
4-5 Accelerando: Cacophony can immediately take the Dash and Disengage actions.
6 Sinister Coda: Cacophony immediately uses its Catastrophe Calliope ability, with the DC increased to 21.

Once this reaction has been used, it cannot be used again until it's initial condition has been met.  This reaction can be triggered even if Cacophony has already used its reaction this round.