Simple solution is “resistant damage” - damage taken by burning your life force to power spells can only be healed by natural healing, not magical healing. It’s tracked separately, and similar to subdual damage, you add it together with normal damage to determine if the character reaches 0HP. If you choose to go this route, I suggest that HP not be your primary fuel for spellcasting, but rather have the patron grant a class feature that allows “overcasting” by burning one’s life force to power additional spells after you’ve run out of normal spell slots.
With root, YouTube URLs will open in the app by default. Without root, they won’t. Otherwise, there’s not a huge difference.