Whispers of the Shadows: Isabella can cast spells as a 10th-level Bard. Her spellcasting ability is Charisma (spell save DC 17, +9 to hit with spell attacks). She has the following Bard spells prepared:

Cantrips: Vicious Mockery, Prestidigitation, Minor Illusion
1st-level (4 slots): Dissonant Whispers, Faerie Fire, Healing Word, Tasha's Hideous Laughter
2nd-level (3 slots): Crown of Madness, Suggestion, Blindness/Deafness
3rd-level (3 slots): Bestow Curse, Fear, Major Image
4th-level (3 slots): Dimension Door, Hallucinatory Terrain
5th-level (2 slots): Mislead, Modify Memory

Evasion: When Isabella is subjected to an effect that allows her to make a Dexterity saving throw to take half damage, she instead takes no damage if she succeeds on the saving throw, and only half damage if she fails.

Multiattack: Isabella can make three attacks during her turn: two with her Bluesteel Rapier and one with Kuro's Mistake.

Bluesteel Rapier: +15 to hit, reach 5 ft., one target. Hit: (1d8 + 9) piercing damage plus (1d12) acid damage.

Kuro's Mistake: +14 to hit, range 60 ft./180 ft., one target. Hit: (3d6 + 8) radiant damage.

Shadow Step: Once per turn, Isabella can use a bonus action to teleport up to 60 feet to an unoccupied space she can see in dim light or darkness. This ability allows her to maneuver swiftly and evade attacks

Uncanny Dodge: When an attacker that Isabella can see hits her with an attack, she can use her reaction to halve the attack's damage against her.