Arachne Matriarch

Arachnid Ancestry. The Arachne has advantage on saving throws against being Charmed, and magic can't put the Arachne to sleep.

Spider Climb. The Arachne can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Walker. The Arachne ignores movement restrictions caused by webbing.

Web Sense. While in contact with a web, the spider knows the exact location of any other creature in contact with the same web.

Legendary Resistance (3/Day). If the Matriarch fails a saving throw, she can choose to succeed instead.

 Magic Resistance. the Matriarch has advantage on saving throws against spells and other magical effects.

Spellcasting. The Matriarch is a 20th-level spellcaster. Her spellcasting ability is Charisma (spell save DC 20, +11 to hit with spell attacks). the Matriarch knows the following sorcerer spells: 

Cantrips (at will): Guidance, mending Infestation, sacred flame, Thaumaturgy

1st level (4 slots): bane, command, shield, absorb elements

2nd level (3 slots): hold person, silence, web

3rd level (3 slots): bestow curse, dispel magic, counterspell, fear

4th level (3 slots): Banishment, Charm monster, polymorph, Conjure woodland beings

5th level (3 slots): contagion, cloudkill, conjure elemental, dense macabre

6th level (2 slots): Blade barrier, harm

7th level (2 slots): Divine word, draconic transformation (range of touch) 

8th level (1 slot): feeblemind

9th level (1 slot): true Polymorph, Imprisonment

Innate Spellcasting. The Matriarch's innate spellcasting ability is Charisma (spell save DC 20). She can innately cast the following spells, requiring no material components:

At will: dancing lights, detect magic, locate creature

3/day each: Polymorph, conjure animals, reincarnate

1/day each: prismatic spray, Teleport.

Multiattack. the Matriarch can make four attacks with its Cocooning limbs. and two attacks with its claws 

Cocooning Limbs. Melee weapon attack +11 to hit. reach 10 ft. one target. hit: 30 (6d10) bludgeoning damage. and the target is grappled (Escape DC 18). while Grappled in this way the target is also restrained. the Matriarch has Eight Legs. each of which can Grapple one Target.

Claws. Melee weapon attack +11 to hit, reach 10 ft. one target. hit: 30 (3d10+15) Slashing damage. 

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one creature. Hit: 40 (4d20) piercing damage plus 20 (2d10+10) poison damage.

Swallow. The Matriarch makes one bite attack against two large or smaller targets it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is Blinded and Restrained, it has total cover against attacks and other effects outside the toad, and it takes 35 (4d10+15) acid damage at the start of each of the Matriarch's turns.  If the Matriarch dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.

As an action a creature can try and force the Matriarch to regurgitate. the Matriarch must make a DC 20 constitution saving throw or regurgitate all swallowed creatures. 

If a creature is reduced to 0 hit points by the acid Damage, it dies instantly and the Matriarch lays an Egg made from the creatures digested remains 1d4 hours later. after the egg Hatches 1d6 hours after its laid, a new Arachne is born from it. the Born Arachne is the same race as the digested creature and has the same memories, skills and abilities as that creature. the Arachne will see the Matriarch as a mother figure. 

Enslave. The Matriarch targets one creature it can see within 30 feet of it. The target must succeed on a DC 15 Wisdom saving throw or be magically charmed by the Matriarch until the Matriarch dies or until it is on a different plane of existence from the target. The Charmed target is under the Matriarch's control and the Matriarch and the target can communicate telepathically with each other over any distance.

if a Dispel magic spell is cast on the target at 8th level, the charm also ends. 

Dexterous legs: The Arachne can take the Dash and disengage actions as a bonus action.

The Matriarch can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The Matriarch regains spent legendary actions at the start of her turn.

Cast a Spell (Costs 1–3 Actions). The Matriarch expends a spell slot to cast a 1st-, 2nd-, or 3rd-level spell that she has prepared. Doing so costs 1 legendary action per level of the spell. 

Enslave. The matriarch uses the Enslave action