Expecto Patronum

You summon a spirit protector which appears in an unoccupied space next to you. The spirit appears to be angelic, fey or natural (your choice), but appears incorporeal none the less. The spirit disappears when the spell ends. If a enemy comes within 15 feet of you, the spirit will cause them harm for every turn they are in range. The enemy will suffer 3d8 radiant damage upon a failed Wisdom saving throw, or half upon a success.
At Higher Levels. The damage increases by 1d8 for each spell slot level used above 3rd.