Varric's Mass Modified Mage Armor

You give up to 8 willing creatures within range who aren't wearing armor a protective magical force that surrounds them until the spell ends. Their base AC becomes 13 + their Dexterity modifier. The spell ends for a particular target if that target dons armor or if you dismiss the spell as an action.

For a 6th level slot or higher, you can affect double the number of creatures for each additional spell slot level used.  When ritual casting, consider the effective level of this spell the highest spell slot level you can use.