Starting at 2nd level, your quick thinking and agility allow you to move and act quickly. You can take a bonus action on each of your turns in combat. This action can be used only to take the Dash, Disengage, or Hide action.

Echoes of those who have died cling to you. Whenever you finish a short or long rest, you can choose one skill or tool proficiency that you lack and gain it, as a ghostly presence shares its knowledge with you. You lose this proficiency when you use this feature to choose a different proficiency that you lack.

As you nudge someone closer to the grave, you can channel the power of death to harm someone else as well. Immediately after you deal your Sneak Attack damage to a creature on your turn, you can target a second creature that you can see within 30 feet of the first creature. Roll half the number of Sneak Attack dice for your level (round up), and the second creature takes necrotic damage equal to the roll's total, as wails of the dead sound around them for a moment.

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Starting at 5th level, when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack's damage against you.

Beginning at 7th level, you can nimbly dodge out of the way of certain area effects, such as a red dragon's fiery breath or an ice storm spell. When you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.

You manifest an aspect of your patron's dreadful power. As a bonus action, you transform for 1 minute. You gain the following benefits while transformed:

You can transform a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

The appearance of your Form of Dread reflects some aspect of your patron. For example, your form could be a shroud of shadows forming the crown and robes of your lich patron, or your body might glow with glyphs from ancient funerary rites and be surrounded by desert winds, suggesting your mummy patron.

Your patron gives you a grimoire called a Book of Shadows. When you gain this feature, choose three cantrips from any class's spell list. The cantrips do not need to be from the same spell list. While the book is on your person, you can cast those cantrips at will. They don't count against your number of cantrips known. Any cantrip you cast with this feature is considered a warlock cantrip for you. If you lose your Book of Shadows, you can perform a 1-hour ceremony to receive a replacement from your patron. This ceremony can be performed during a short or long rest, and it destroys the previous book. The book turns to ash when you die.