but I do have a question does the SetNthIEMagnitude save or would I need to set it every load? (Im pretty sure theres like a OnLoad or something like that so it shouldnt be hard but I just need to know so i can if i need to lol)
The fact is, I don't remember for sure.
I'm 90% sure it doesn't. But your variable holding the magnitude it
should have is saved, and the command you're looking for is GetGameLoaded. Or as I mentioned above, just set it every time you remove it as well as every time you add it. Oblivion scripts are very processor-efficient, there's no reason to cut corners.
In case it's not entirely clear, here's how the process works internally: when you add the ability to the player, Oblivion checks the ability's magnitude, internally calls ModAV on the appropriate attribute (Magicka in this case), and adds an Active Effect (AE) record to the player which points back to the ability. The AE stores a magnitude value for display, but that's all it's used for. If you later remove the ability, instead of using the AE magnitude, Oblivion checks the base form's magnitude again and calls ModAV for the inverse value. Except for when it's added and when it's removed, the ability's magnitude is not checked; so if you save the game then quit and reload, the base spell has a magnitude of 0 again but the effect on the player is still at whatever magnitude it had when you saved. You need to change it back before removing the effect or the inverse-ModAV will be incorrect; but you
don't need to set it as soon as the game loads, because from the player's perspective everything is as it should be. (Again, better safe than sorry -- I'd set it on game load AND right before removing it.)
I actually took advantage of this in Willful Resistance to use the same two base abilities (resist and weakness) on every actor in the game: I set them to different magnitudes for each actor, because once applied, changes to the base form don't matter. Immediately before removing an ability, I set it back to what it was when I applied it, so it came away clean. The downside is that other mods checking those actors' abilities might not get the right info, and for that reason Willful Resistance is one of the mods I'll be switching over to Formulator once it's ready; but in your case, with only the player being affected, it should be safe enough.