Vernän's Arcane Aura

A magical cylinder of arcane force springs into existence 15 foot diameter circle defending from the triggering attack. Nothing can physically pass through the aura, it has an AC of 15 and 100 hit points and lasts until the end of your next round, shielding you and anyone else inside from damage. If the aura is broken before the time is up, everyone inside must make a dexterity saving throw or take 4d6 force damage.

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the AC of the barrier increases by 1 and the health increases by 10 for each spell slot above 5th level.