Homebrew
Glasya’s innate spellcasting ability is Intelligence (spell save DC 20, +13 to hit). She can innately cast the following spells, requiring no material components:
Hear Name. Glasya hears her name when spoken, regardless of distance or planar boundaries. If a creature speaks her name three times in the same breath, Glasya learns the creature’s name and precise location, and can perceive through the speaker's senses for the next 10 minutes (60 rounds). She remains aware of her surroundings while using this connection. Glasya can choose to terminate this connection early, requiring no action. Once per day, Glasya can cause a lawmaker or law arbiter within 60 feet of the creature whose senses she shares to recall or create legal wording that favors the speaker. This ability functions like the Suggestion spell (DC 20 Wisdom saving throw to resist).
Contractually Obligated. Glasya has advantage to hit creatures under an infernal contract and when she hits such creatures she delivers an additional 9 (2d8) damage of a type the target is most vulnerable to. A creature bound under an infernal contract also makes all saving throws against effects originating from Glasya with disadvantage.
Evasion. If Glasya is subjected to an effect that allows her to make a Dexterity saving throw to take only half damage, she instead takes no damage if she succeeds on the saving throw and only half damage if she fails, provided she isn't incapacitated.
Devil's Sight. Magical darkness doesn't impede Glasya's darkvision.
Magic Resistance. Glasya has advantage on saving throws against spells and other magical effects.
Sneak Attack (1/Turn). Glasya deals an extra 21 (6d6) damage when she hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of another creature hostile to the target that isn't incapacitated and Glasya doesn't have disadvantage on the attack roll. Glasya does not need advantage on the attack roll to use Sneak Attack against a creature if she is within 5 feet of it, no other creatures are within 5 feet of her, and she don't have disadvantage on the attack roll.
Nimble Defense. While Glasya is wearing light or no armor and wielding no shield, her AC includes double her Dexterity modifier.
Multiattack. Glasya makes four Knife in the Dark or Throw the Book at 'Em attacks.
Knife in the Dark. Melee Weapon Attack (shortsword): +11 to hit, reach 10 ft., one target. Hit: 7 (1d6 + 4) slashing damage, and the target must make a DC 20 Constitution saving throw, taking 21 (6d6) poison damage on a failed save, or half as much damage on a successful one.
Throw the Book at 'Em. Ranged Spell Attack: +13 to hit, range 60 ft., one target. Hit: 44 (8d10) psychic damage.
Connected Clauses (Recharge 5-6). Glasya assaults a creature she can see within 150 feet of her with a burst of legalese. The target then recites related legal jargon to as many as three other targets, each of which must be within 30 feet of the first target. A target must make a DC 20 Wisdom saving throw, taking 45 (10d8) damage on a failed save, or half as much damage on a successful one. The damage type inflicted is of a type the first target is most vulnerable to. If the first target has no vulnerabilities, the damage is psychic.
Elegant Step. Glasya teleports up to 30 feet to an unoccupied space she can see.
Sharpened Tongue. Glasya's razor-sharp wit demoralizes a foe. She makes a Charisma (Persuasion) check contested by a creature's Wisdom (Insight) check. The target must be able to hear Glasya. If she succeeds the check, the target has disadvantage on attack rolls against her and can't make opportunity attacks against her. This effect lasts for 1 minute, until another creature hostile to the target attacks it or affects it with a spell, or until Glasya and the target are more than 60 feet apart.
Legendary Action Uses: 3. Immediately after another creature's turn, Glasya can expend a use to take one of the following actions. Glasya regains all expended uses at the start of each of their turns.
Elegant Step. Glasya uses her Elegant Step to teleport up to 30 feet to an unoccupied space she can see.
Hard Logic. Glasya targets one creature within 60 feet that can hear her with a legal argument that justifies some profane truth. It must succeed on a DC 20 Wisdom saving throw or take 18 (4d8) psychic damage and have disadvantage on its next saving throw before the end of its next turn, burdened by the struggle of knowing that Glasya is making perfect sense even though you want her to be wrong.
Cast a Spell (Costs 2 Actions). Glasya casts a spell from her Innate Spellcasting list.
Protect The Family. Glasya causes an ally within 30 ft of her that can hear her to immediately make an attack using its reaction.
On initiative count 20 (losing initiative ties), Glasya can take the following the following lair action while in her seat of power in Narakkas:
An Offer You Can't Refuse. Glasya makes an "offer" that forbids or requires a specific action. The offer is limited to a sentence or two, and magically influences creatures that can hear and understand Glasya within 60 feet of her. The offer must be reasonable - requiring the creatures to throw themselves onto their own weapons, immolate themselves, roll around in lava, or do some other obviously harmful act automatically negates the offer. If she proposes an offer that is not possible to execute ("All Evarans are legally obligated to jump into a volcano" when there is no volcano present), the offer is also negated. Until the next initiative count 20, any creature that ignores her offer takes 18 (4d8) psychic damage and must succeed on a DC 20 Charisma saving throw or be stunned until the end of its next turn. Glasya may not propose the same offer two rounds in a row.Infernal Loophole. When Glasya has 25% of her maximum hit points remaining or less, she can use An Offer You Can't Refuse without the prohibition against obviously harmful courses of action provided that it would not cause a creature to make death saving throws. She may also make the same offer multiple times in a row (i.e., "Hold your Breath", decreed for 2+ rounds). If she proposes an offer that is not possible to execute, the offer is still automatically negated.
The region within 1 mile of Glasya's lair is warped by her will, creating one or more of the following effects. These effects fade after 2d10 days if Glasya dies:
Twisting Justice. Law and order become corrupt. Any spell that reveals truth (like Zone of Truth, Detect Thoughts) requires a successful DC 15 spellcasting ability check to function, and any other effect that reveals truth (Ring of Truth-Telling) requires a DC 15 Charisma saving throw to function. On failure, the spell or effect twists subtly to favor deceit. For example, the effect of Zone of Truth may reverse such that a creature cannot willingly speak the truth, or a Ring of Truth Telling may grant advantage unreliably. The check or saving throw must be repeated for each new use.
Fortune Favors the Fearless. Audacious plans against overwhelming odds may have slim margins for victory but high rewards. If successfully executed, such plans may reap even better rewards than envisioned, provided the plans do not in some way threaten Glasya or her internal standing.