You can weave magic around yourself for protection. When you expend mana to cast a spell, you can simultaneously use a strand of the spell’s magic to create a magical ward on yourself that lasts until you finish a long rest. The ward has health equal to your level + your spellcasting ability. Whenever you take damage, the ward takes the damage instead. If this damage reduces the ward to 0 health, you take any remaining damage.
While the ward has 0 health, it can’t absorb damage, but its magic remains. Whenever you expend mana to cast a spell, the ward regains an amount of health equal to the mana you expended.
When a creature that you can touch or see within 9 meters of you takes damage, you can use your reaction to cause your ward to absorb that damage. If this damage reduces the ward to 0 health, the warded creature takes any remaining damage.
Once you create the ward, you can’t create it again until you finish a long rest.