Devil’s Sight. Viserys can see normally in darkness, both magical and nonmagical, to a distance of 120 ft.

Evasion. If Viserys is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, she instead takes no damage if it succeeds on the save and only half damage if it fails. 

Mobile. When she use the Dash action, difficult terrain doesn't cost her extra movement on that turn. When she make a melee attack against a creature, you don't provoke opportunity attacks from that creature for the rest of the turn, whether you hit or not.

Assassinate. Viserys advantage on attack rolls against any creature that hasn’t taken a turn in the combat yet, and any hit she scores against a creature that is surprised is a critical hit.

Shapechange. As an action, you can change your appearance and voice. You determine the specifics, including your coloration, hair length, sex, height, weight, and can change your size between Medium and Small. You can look like another race, though none of your game statistics change. Their clothes also change thanks to the Armor of Glamour. 

Dark One’s Blessing. When Viserys reduces a hostile creature to 0 HP, she gains 10 temp HP.

Pact Weapon. You can then dismiss the weapon, shunting it into an extradimensional space, and it appears whenever you create your pact weapon thereafter. Pacted weapon is a Venom Dagger of Warrning so she can never be suprised by an attacer within 60 feet.

Multiattack. Viserys makes three Eldritch Blasts or two Venom Dagger strikes.

Venom Dagger. Melee Attack Roll: +11, reach 5 ft. Hit: 8 (1d4 + 6) Piercing damage plus 20 (6d6) Poison damage, and the target has the Poisoned condition until the start of the assassin’s next turn.

Eldritch Blast. Ranged Attack Roll: +9, range 300 ft. Hit: 6 (1d10) Force damage and the target is slowed by 10 feet till the end of it's next round.

Cunning Action. Viserys takes the Dash, Disengage, or Hide action.

Misty Escape. Viserys can use the misty step twice per short rest.

Ghostly Form (3/long rest). While the ghost step tattoo is on her skin, she can expend 1 of the tattoo’s charges to become incorporeal until the end of her next turn. For the duration, she gain the following benefits:- resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks.
- can’t be grappled or restrained.
- can move through creatures and solid objects as if they were difficult terrain. If you end your turn in a solid object, you take 1d10 force damage. If the effect ends while you are inside a solid object, you instead are shunted to the nearest unoccupied space, and you take 1d10 force damage for every 5 feet traveled.

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