Sanguimancy

You have studied forbidden magics and learned blood magic, the ability to trade vitality for power!

• You gain 3 blood dice, which is a d6. You can use these to activate blood techniques once per turn. All blood techniques will ask you to roll one of your blood dice, when you do you take half of the roll rounded up. You can choose to empower these dice before you roll and take the full result as damage, this damage can't be mitigated in any way. You regain all your blood dice at the end of a long rest.
• Blood Technique, Determination: When you roll a concentration check you can spend a blood dice and add the number rolled to you concentration check. If you empower this dice roll the damage you deal to yourself does not trigger a concentration check.
• Blood Technique, Precision:  When you roll a spell attack you can roll your blood dice and add the number rolled to your spell attack.
• Blood Technique, Strengthen: once per day you can use your action to spend 1-3 blood dice and regenerate a spell slot equal to the amount of blood dice you spent. These blood dice are always empowered and you take max damage from them, 6 per die.

(Author note and message to my players: In my homebrew you have to have my permission or an items that grants you access to this feat in order to take it.)