Your mastery over the arcane lets you alter the course of spells targeted at you. If the spell is of 5th level or lower you alter its course and can send it back to the initial caster as if it were your own spell; having to make a spell attack roll or the initial caster now making the saving throw. If the spell if of 6th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell’s level,  on a success you alter the spell’s course, on a failure the spell maintains its original course towards affecting you. 

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the spell’s course is affected if it is of level less than or equal to the level of spell slot you used.