Bone Shield

Five whirling bones enchanted with necromantic energy appear in your space. Until the spell ends, the bones whirl around in in a protective aura, shifting with your motions as to not impede your locomotion. You can end the spell early by using an action to dismiss it.

As long as you have four or more bones in your shield, you have three-quarters cover, granting you a +5 bonus to your AC and Dexterity saving throws. If you have three or less bones in your shield, you have half cover instead, granting a +2 bonus to your AC and Dexterity saving throws.

Whenever an attack misses you, or whenever you succeed on a Dexterity saving throw, make a Constitution saving throw as if you were maintaining concentration on a spell. The DC of the constitution saving throw is equal to the attack roll or DC of the spell that provoked the Dexterity saving throw. On a failed save, one of the bones from your shield is destroyed. The bones last until the spell ends, or until all bones in the shield have been destroyed.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, you create one additional bone in your shield for each slot level above 4th.