Spell Immunity. Lady Anchor is immune to the spells Heat Metal and Burning Hands.

Adamantine Anchor. Lady Anchor is immune to critical hits.

Immutable Form. Lady Anchor is immune to any effect that will alter her form.

Iron Body. Lady Anchor has advantage on Constitution saving throws. Additionally, her creature type counts as both Undead and Construct.

Dark Form. All bright light within 120 feet of Lady Anchor becomes dim light, and all dim light becomes darkness. While within 60 feet of Lady Anchor, a creature's darkvision is ineffective (not including her own).

Undead Fortitude. When Lady Anchor drops to 0 hit points, she can make a Constitution saving throw at advantage against the amount of damage taken. If she succeeds, she is instead at 1 hit point.

Spellcasting. Lady Anchor is a 11th-level spellcaster. Its spellcasting ability is Strength (spell save DC 21, +11 to hit with spell attacks). Lady Anchor has the following Sorcerer spells prepared:
Cantrips (at will): Poison Spray, Thorn Whip, Shape Water, True Strike
1st level (4 slots): Chaos Bolt, False Life, Magic Missile, Shield

2nd level (3 slots): Darkness, Blur, Enlarge/Reduce

3rd level (3 slots): Fear, Fireball, Lightning Bolt

4th level (3 slots): Blight, Banishment, Watery Sphere

5th level (2 slots): Synaptic Static, Animate Objects

6th level (1 slot): Chain Lightning

7th level (1 slot): Prismatic Spray

Multiattack. Lady Anchor uses Anchor Slam and casts Thorn Whip or uses her Choking Chain, and uses her Frightening Presence. Or, she casts a spell and casts Thorn Whip.

Anchor Slam. Melee Weapon Attack: +12 to hit, reach 5 ft., 1 target. Hit: 5d12+7 piercing damage. The target's speed is also reduced to half until the end of their next turn.

Frightening Presence (1/day). Each creature of Lady Anchor's choice within 60 feet of her must make a DC 19 Wisdom saving throw or be Frightened and Stunned for one minute. An affected creature can remake the saving throw at the end of each of their turns, ending the effect on a success.

Choking Chain (Recharge 5, 6). Lady Anchor targets two creatures she can see within 30 feet of her. A target must make a DC 20 Strength saving throw or become grappled and restrained by her chains. An affected creature is considered to be at half of their held breath when this grapple starts. An affected creature takes 5d4 piercing damage at the start of each of their turns, and can repeat this saving throw at the end of each of their turns.

Etherealness (Recharge 6). Lady Anchor becomes incorporeal and under the effects of the Gaseous Form spell. She can still cast spells while in this form, and reverts back to her normal form after taking 20 damage.

Lady Anchor has three Legendary Actions. She can only use one Legendary Action at a time and only at the end of another creature's turn. She regains all spent Legendary Actions at the start of her next turn.

Piercer (Costs 2 Actions). Lady Anchor makes one Anchor Slam attack.

Magical Interlude. Lady Anchor casts a spell.

Movement. Lady Anchor moves up to her speed without provoking opportunity attacks.