Eelin's Arcane Armor

You cause invisible barriers of magical force to appear around yourself and up to three willing creatures within range.  For the duration, all affected creatures have a +2 bonus to AC and take no damage from magic missile.  In addition, whenever an attacker within 120 ft. misses an affected creature with an attack roll, a magical dart erupts from the barrier and strikes the attacker.  The dart automatically hits a target not affected by shield, and deals 1d4 + 1 force damage.

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the AC bonus increases by 1 for each slot level above 6th.