Eldritch Sacrifice

You can fire powerful eldritch energy blasts from your arms; in doing so you often injure your arms but not to worry they slowly heal over time due to the sheer amount of energy pulsing through them. The power level of any eldritch arm blast you fire is randomly determined by rolling a d4, the higher the number you roll the more power you will use and therefor the more damage you will do to the enemies but also your own body. Over time you will gain more control over the energy in your arms and be able to roll multiple d4's and take whichever roll you please. At later levels you will also be able to fire your eldritch arm cannons as a bonus action and gain an ultimate attack that does huge damage but exhausts your body significantly.

Eldritch Cannon (rules)

Your main form of attack is your eldritch cannon. This cannon is a beam of energy that fires from your arm (your hands must be free to use it), when you do so roll a D4 (the number will decide how much power the arm beam has and therefor how much damage you take from using your eldritch cannon). If you roll a 1: your eldritch cannon fires from your pointer and middle fingers (if you have already used these fingers the blast fires from your ring and pinky fingers) on whichever hand you choose. If you roll a 2: your eldritch cannon fires from your wrist on whichever hand you choose. If you roll a 3: your eldritch cannon fires from your elbow on whichever arm you choose. If you roll a 2: your eldritch cannon fires from all the way up to your shoulder on whichever arm you choose. The higher the number you roll the more damage your blast does to enemies and yourself. 

Eldritch Cannon (Power level:1)

When you roll a 1 on your eldritch cannon power level die the blast with fire from your pointer and middle fingers (if you have already used these the blast fires from your ring and pinky fingers) destroying them completely in the process.

Eldritch Cannon (Power level:2)

If you roll a 2: your eldritch cannon fires from your wrist on whichever hand you choose, completely destroying it and everything below in the process.

Eldritch Cannon (Power level:3)

If you roll a 3: your eldritch cannon fires from your elbow on whichever arm you choose, completely destroying it and everything below it in the process.

Eldritch Cannon (Power level:4)

If you roll a 4: your eldritch cannon fires from just below your shoulder on whichever arm you choose, completely destroying it and everything below it in the process.

Unnatural Regeneration

The sheer amount of energy constantly surging through your arms gives them extraordinary healing abilities. However, doing this takes a toll on your body. The more healing you apply to your arms the larger the toll will be only your body, costing you HP.

You touch your own arm/s and regenerate an amount (your choice) of your arm/s that was damaging by using your eldritch cannon. The more healing you apply to your arms the larger the toll will be only your body, costing you HP. For every stage of arm damage that you heal take 1d4. This resets on a short rest.

Every time the damage of your eldritch arm cannon increases as does the toll on your body to heal the damage it does to yourself. With every 2 eldritch cannon damage increases the damage to yourself to heal will go up by 1 die type. (The level 20 blast is only a d12 of damage to yourself because it takes out your entire arm, so you deserve some slack).

Controlled Energy

You have begun to gain control over the immense amounts of energy surging through your arms. When you roll the power level for your arm blast you can roll a second time and use either number. If you happen to roll two of the same number, you will instantly gain a critical hit for that attack.

Multi Blast

You have enough control over your eldritch powers that you can handle blasting energy from both arms at once. You can now fire off an eldritch cannon blast as bonus action attack.

Limitless Beam (Ultimate)

Once per day your power levels spike and you gain the ability to let off a blast that goes beyond your limit and reaches power level 5. This blast requires you to hold both of your arms together to fire it. This blast also destroys both of your entire arms and shoulders in the process, but the amount of power from the blast allows your unnatural regeneration to work beyond its limit as well. Directly after you fire the devastating blast your arms begin to regenerate at incredible speeds, restoring them both completely with no cost to your HP. But instead gives you once level of exhaustion after use.

Complete Control

Now that you have been using your eldritch arm cannons for a solid amount of time you have gained a deeper connection to and understanding of the energy that flows through them. With your newfound knowledge of your energy, you have near complete control of your power. When you roll to determine the power level of your arm blast you can now roll 3d4 and choose any of the numbers.