Echinacea's Defensive Dome

If you or a creature you can see within 30 feet of you is hit with a ranged weapon or spell attack, you can use a reaction to summon a dome of flame centered on a point you choose within range, and this dome lasts for the duration of the spell or until it is broken. The dome is 15ft in radius and has 30 hit points. The dome absorbs damage from attacks and spells from outside it until its hit points are reduced to zero, at which point excess damage carries over onto creatures and objects inside the dome. Spells can be cast from friendly creatures inside the dome but and ranged or melee attacks made from inside will damage the dome.

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher the dome's hit points increase by 10 for each spell slot above 3rd.