Alexander's Missile Defence

As a reaction you conjure up a shield to protect you and your allies from incoming missiles, the shield is a vertical semicircle that is 30ft long and stretches 15ft back towards the caster on each edge, and lasts for one round. While the shield is up, any projectiles that come into contact with it are stopped in the air for the duration. If a single projectile exceeds 30 points of damage the shield fails and the projectile continues onto its target, and any other projectiles that have been caught by the shield fall to the ground. The shield is immune psychic and poison damage.

As a bonus action on your turn, you can choose to fire the collected projectiles back at the enemy. Make a ranged spell attack for each collected projectile, on a hit each projectile deals 1d8 piercing damage, or 1d10 bludgeoning damage if the projectile is large or bigger. Each projectile can only target one creature, unless the projectile is big enough to reasonably hit more.