Level 7: Friend of the Dark
Level 11: One with Darkness
Level 15: Deep in the Dark
Starting at 7th level, you can cast the Darkness spell without a spell slot or components. Once you have done so, you must finish a short rest before you can do it again.
Also, when you cast the Darkness spell, you can see through its magical darkness as if it wasn't there.
Starting at 11th level, as a bonus action, you can become part darkness until the beginning of your next turn. In this state, you look like a shadow of yourself and you do not make any sound while moving, so you gain advantage to your Stealth checks.
Starting at 15th level, as an action, you can partially move through the Shadowfell until the beginning of your next turn. While in this state, you are partially insubstantial, can move through solid objects and have resistance to non-magical damage. If you end your turn inside a solid object, you will be automatically pushed back to your point of entry and suffer 4d6 force damage.