Counter-measures of the Living Artillery

The caster draws a circle around them, infusing the ring with protective fire runes. If the caster intends to protect multiple creatures, then the circle must encompass all of them. It may take more than one action to draw the circle around a large number of creatures. The magic of the spell lasts as long as the caster keeps concentration on the spell. 

Once the circle is drawn, if any projectile or ranged spell is cast targeting a creature inside, fiery projectiles launch out at the incoming projectile, reducing the damage by 2d6 + INT. If the damage is reduced to 0, then the incoming projectile either burns up if physical, or is dispelled if magical. 

At higher levels, the damage reduction is increased by 1d6 per spell level above 2.