Astral Sacrifice

You sacrifice your own vitality to the Weave, offering your strength in exchange for magical prowess. When you cast this spell, your maximum HP gets reduced by 10, and you gain an additional temporary 1st level spell slot, 20 maximum health reduction for one 2nd level spell slot, 30 maximum health reduction for 3rd level spell slot.

You may cast this spell multiple times to gain additional temporary spell slots, reducing your maximum HP by 10 each time. Beware, however: If your maximum HP gets reduced to 0 this way, your body and your very soul get disintegrated into magic and become one with the weave, killing you instantly. Only divine intervention or a wish spell can bring you back from this kind of death.

You lose all additional spell slots, and regain your maximum HP after a long rest