Magic Resistance resist mystys eyes that aren't magic but isntead eyes with powers, the example it's how they resist the eyes of pretrification of Medusa, so that mean they resist/cancel (depending in the rank) mystic in general, so aside from the physical mystic like the punch of deku, the other quircks are resisted nulled. About Clarent, the problem it's that Clarent equal the Balmung of Siegfried which by the
calcs would be Low 6-B (2.9 Teratons), yeah in the case against Fafnir Siegfried is powered because it's fighting against a dragon but Mo-chan have dragon blood so Siegfried also it's powered fighting against her, to point it's that Clarent it's fatal to Deku, even the shockwave in the best case would only left him half-dead, he on top of need to evade the beam itself (which can move while relasing) need to evade the shockwave. About the Mana Burst, my bad there, I only know that there are a amp so I created a thread to see how much it's the amp, and in the case of Mo-chan his Mana Burst turn his rank C Clarent in ran A+ Clarent Blood Arthur, which equal the Balmung of Sieg.
I didn't wanted to say things relationed with the upgrade, but because it's the best way I find to express why Clarent it's so dangerous to Deku it was why I bring that here, currently still haven't be decided to which tier the servants itself would backscale but the definitive thing is that at least the NP are tier 6, so I guess for the moment the only thing tier 6 would Clarent Blood Arthur while Mo-chan itself still is tier 7?