Adamantine Destruction. The ??? destroys any adamantine, even magical adamantine, within 10 feet of it.

Huh. The ??? always moves first and always moves last.

Spellcasting. The ??? is a 0-level spellcaster. Its spellcasting ability is Constitution (spell save DC 22 and a half, -10 to hit with spell attacks). The ??? has following Barbarian spells prepared:
Cantrips (at will): None
1st level (-5 slots): None

What the Actual [REDACTED]. Reading this stat block gives the DM a stroke and makes them pass out. Directly after rolling for initiative, each player gets 3 turns to remove this unholy abomination from the Material Plane.

Even More Bullsh*t. If the ??? is lowered to 0 Hit Points, it gains 1 Health and Immunity to All damage. However, it cannot take any Actions, Bonus Actions, or Reactions for one turn, and at the end of that turn, the ??? takes 1 Necrotic damage. This damage ignores Immunity.

Multi(?)attack. The ??? makes no Nonexistent Glaive attacks and two thirds of a Weird Cone attack.

Weird Cone. Melee Weapon Attack: +20000 to hit, reach 0 ft., 100 targets. Hit: 500,000 (0d4 + 0) Psychic damage.

Nonexistent Glaive. Ranged Spell Attack: +-5 to hit, range 10 ft Emanation., 1 target. Hit: 0 (40d20 + 500) Necrotic damage.

Utter Confusion. The ??? makes a duplicate of itself. The duplicate uses the exact same stat block and does not lack this action. The creature that used this action drops to 0 Hit Points immediately.

Befuddling Blitz. The ??? moves up to twice its Speed without provoking Opportunity Attacks, yet its destination must be within 5 feet of a creature. The creature then gets an Opportunity Attack on the ???.

Reaction. This is not a reaction. Any questions?