Counter-Conductivity

You generate enough harmful energy to ward of that kind of energy in an area. As you cast this spell, you take 2d6 in damage of whatever type you choose. As the damage resolves you create a ward centered around yourself which grants all allies in it including yourself immunity to the damage type you chose while casting this spell. You still have to make a saving throw against effects that do that damage type and are still affected by all effects of a the mitigated effect (ex. if an enemy wizard casts Sickening Radiance and you had, on the turn just before them, cast Counter-Conductivity with radiant as the damage type, you would suffer no radiant damage still have to make a Constitution saving throw or suffer 1 point of exhaustion and if your Arcane Trickster was invisible and in the sphere, they would lose invisibility).

At Higher Levels. When you cast this spell with a spell slot of 4th level or higher, the damage dealt to yourself increases by 1d6. Also, when you cast this spell using a spell slot of 4th level or higher, the sphere increases by 5 feet for every level above 3rd.