Beast the One, Space Beast Progenitor

Magic Resistance. The One has advantage on saving throws against spells and other magical effects.

Shadow Stealth. While in dim light or darkness, The One can take the Hide action as a bonus action.

Legendary Resistances. The One has 4 legendary resistances per turn.

Multiattack. Can make 4 Chomp, Swipe, or Fire Salvo attacks.

Mandibles. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 34 (5d10 + 7) piercing damage, and the target is grappled (escape DC 19). Is target is medium or smaller, the escape attack is at disadvantage. Until this grapple ends, the target is restrained, and the ancient deep crow can't use its mandibles on another target. 

Swipe. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 31 (7d6 + 7) slashing damage. Target makes a DC 17 Strength saving throw. On failure, target is knocked prone and pushed back 20 feet. This attack optionally can also grapple instead (escape DC 19). This attack critically hits on a 17-20.

Fire Salvo. Ranged Weapon Attack: +13 to hit, range 200 ft., 1-3 targets. Hit: 39 (6d10 + 6) fire damage. This also ignites the ground where the fireballs hit in a 15 foot radius, causing an additional 2d10 fire damage to any ending their turn.

Regenerate. If a corpse is within 15 feet of The One, they can absorb it into themselves and regenerate 20 HP (small or medium) or 40 (large or larger).

Energy Drain. If a target is grappled by The One, it can draw power from them. Grappled targets lose 1 HP dice and take on one level of exhaustion. If they have spellcasting, instead of an HP dice, they lose 1 spell slot.

4 Per Round

Mandibles. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 34 (5d10 + 7) piercing damage, and the target is grappled (escape DC 19). Is target is medium or smaller, the escape attack is at disadvantage. Until this grapple ends, the target is restrained, and the ancient deep crow can't use its mandibles on another target. 

Swipe. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 31 (7d6 + 7) slashing damage. Target makes a DC 17 Strength saving throw. On failure, target is knocked prone and pushed back 20 feet. This attack optionally can also grapple instead (escape DC 19). This attack critically hits on a 17-20.

Fire Salvo. Ranged Weapon Attack: +13 to hit, range 200 ft., 1-3 targets. Hit: 39 (6d10 + 6) fire damage. This also ignites the ground where the fireballs hit in a 15 foot radius, causing an additional 2d10 fire damage to any ending their turn.

Wing Attack (Costs 2 Actions). The One beats its wings. Each creature within 10 feet of the deep crow must succeed on a DC 19 Dexterity saving throw or take 13 (2d6 + 6) bludgeoning damage and be knocked prone. The One can then fly up to half its flying speed.