You gain the following benefits.
Eyes of the Dark
You have Darkvision with a range of 120 feet and Blindsight with a range of 10 feet. In addition, if a spell you cast creates an area of Darkness, you can see normally through that spell's Darkness.
Strength of the Grave
If you would drop to 0 Hit Points and not die outright, you can make a Charisma saving throw (DC 5 plus the damage taken). On a successful save, your Hit Points instead change to a number equal to your Charisma modifier plus your Sorcerer level. After you succeed on this save, you can't use this benefit again until you finish a Long Rest.