What about poisons/sicknesses and such? Does his Aura also activate in response to ailments? If you just have to treat him as that mushroom-dude from Vinland Saga, it should be fine then.

I just want the villains that Nef has planned to be a threat without being stupidly OP. Sorta ruins the whole nefarious intelligent villain idea if you have a teacher who basically just loltanks through everything and then returns all that damage back to you.