You create an incredibly powerful ward with magically reflective properties. When you cast this as a reaction against a spell targeting you, the caster takes 1d6 force damage for each level of the spell they cast (for example, 1d6 for a first level spell, 2d6 for a second level, and so on). Additionally, the caster makes a saving throw of their spellcasting stat. On a failed save, the spell they cast does not have any effect on you.