Soul Siphon

As a soul siphon, you have the ability to steal parts or all of others' souls to fuel your magic. As a result, your own soul is bolstered and made stronger. You radiate energy and magic, which can sometimes put you in harm's way. When you use souls this way, you are able to expend their power, removing them existence entirely.

Soul Storage

Starting when you choose this origin at 1st level, you can collect souls to augment your magic abilities. When a creature within 30 feet of you dies, you may use your reaction to absorb its soul into your arcane focus. You can do this a number of times equal to your Sorcerer level per long rest. These souls can be used instead of expending spell slots, with two souls equal to a 1st level slot. Souls can be combined to replace higher slots - three souls for a 2nd level slot, five souls for a 3rd level slot, and so on. Your arcane focus can hold a number of souls equal to your CHA modifier (minimum of 1). This increases to twice your CHA modifier at level 10 and three times your CHA modifier at level 18. If you lose your arcane focus, you can spend an hour attuning to a new one, however, you lose all the souls that were stored in the original.

Soul's Edge

Starting at 1st level, you can manipulate the souls in your arcane focus to gain a bonus on one attack roll, ability check, or saving throw equal to a number of souls you choose from your arcane focus. Once you do so, you must finish a long rest before you can use this feature again and the chosen number of souls are expended from your arcane focus. At level 10, the number of souls expended is half the bonus (rounded up).

Souls to Souls

Starting at 6th level, you have the ability to use souls in your arcane focus as sorcery points. Each expended soul used this way is converted into one sorcery point. In addition, the range of your soul collection is extended to 60 feet.

Soul Receptical

At 14th level, you gain control of the power of your own soul, as well as others. You no longer need an arcane focus to collect and store souls, you can do so through your own body. You can also cast spells without material components (those without a gold amount).

Inner Power

Beginning at 18th level, your inner power intensifies. Once per long rest, you can point at any creature that you can see within 60 feet  and use an action to attempt to harvest their still living soul. Roll two D20s. If you get a 20 on each, the target dies instantly, and you gain its soul. If you attempt this on a creature with a CR higher than your level, it automatically fails. If this fails, you must make a CON saving throw equal to your own save DC. On a failed save, you take damage equal to the target creature's CR, and you lose half of your stored souls. You take half as much on a successful save and retain all souls.