Unstable form. This... thing constantly shifts form and can seem Incoherent to those who view it. At the start of combat, all creatures that are not Aberrations, Constructs, or Undead that can see it must succeed a DC 23 Wisdom Saving Throw or be frightened of the Spiral.
Inchoate Speech. It can speak, but the speech is broken and nearly glitch-like. If a creature starts its turn within 50 ft. of it, the creature must roll a DC 20 Constitution saving throw, or feel sickly from the very speech and be poisoned. If a Creature fails by 6 or more, the creature takes 10 necrotic damage per round for 5 rounds as their flesh seems to want to join it.
Legendary Resistance (3/day). It can choose to succeed a saving throw if it fails 3 times a day.
Multiattack. The gibbering mouther makes one bite attack and, if it can, uses its Internal Explosion.
Shift Flesh. Ranged Spell Attack: +10 to hit, reach 30 ft., one creature. Hit: 48 (12d8 + 22) force damage. If the target is Medium or smaller, it must succeed on a DC 19 Strength saving throw or be knocked prone. If the target is killed by this damage, the target's flesh melts into the ground.
Tentacle. Melee Weapon Attack: +12 to hit, reach 15 ft., one creature. Hit: 32 (4d8 + 17) force damage. If the target is Large or smaller, it must succeed on a DC 21 Strength saving throw or be restrained. This creature has 1d8+1 tentacles it can restrain targets with. If the target is killed by this damage, the target's body gets crushed in the tenacle, exploding.
Crushing Tentacle. A creature that is restrained by the tentacles of the creature must succeed a DC 23 Constitution saving throw or take 32 (4d8 + 17) force damage.
Internal Explosion (Recharge 18-20). This thing starts screeching a loud noise, but it is only audible to the target. The target must succeed a DC 20 Constitution Saving Throw, or suffer the effects of the Power Word Kill spell, except the hit points being 70 instead of 100.
It has 4 legendary actions and regains 2 at the start of its turn.
Move. It moves up to its move speed.
Crushing Tentacle (Costs 1 or 2 actions). This being uses Crushing Tentacle on 1 or 2 creatures, using 1 action per creature.
Shield of DM's protection (Costs 4 actions). As a reaction to being hit, roll a 1d10, and that increases the Armor Class by the rolled amount, potentially causing the attack to miss.
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