So let's say you're going along and you find a nice Master-level scroll, for Dead Thrall. You finish the Civil War at level 20-something and you want to parade Ulfric around like a decaying puppet to really show the rebel scum what you think of them. You get out that scroll you've been saving special and cast it on Ulfric, and just when your zombie fantasy Hitler should stand up and start moaning, you find out he's too powerful.
Except that's not right. Ulfric should be about your level, and safely below the level 40 cap on dead thrall, so that should have worked, right?

HAHA NO

Scrolls in vanilla Skyrim do not do quite what you'd think. They don't cast the exact spell that they share a name with. Instead, they cast what is sometimes an identical set of effects, but usually just the main effect at about half magnitude. That scroll of Harmony you thought you were lucky to find? Useless from about just after you stepped back outside Bleak Falls Barrow. It has a magnitude of 12. Let that sink in. If you hit any NPC with that spell, and that NPC is a higher level than 12, the Master-level Illusion scroll will not work. I don't know if you can even find the scroll while enemies weak enough to use it on still appear.

What this mod does is sets the magnitude of the scroll to be at least the same as the spell magnitude. Digging through all the data, it looks like Bethesda intentionally made scrolls awful in order to balance them against regular spells, since scrolls cost no magicka. Perks also don't affect scrolls; an Ebonyflesh scroll is not nearly as good as the spell with the perks. However, they forgot to then make scrolls plausible to obtain, rendering all of the rebalancing pointless. Since I prefer having something that's hard to find but rewarding to something common but useless, I decided to increase the magnitude instead of making scrolls more common. Perks still won't affect it, although I can't honestly imagine why you're putting perks into that spell tree and still preferring scrolls.

But what's that? You want a way to get scrolls? Especially now that you know that with this mod, they won't be as useless as every other time you hoped scrolls might be good? Sure, and thank you for setting me up to shamelessly plug my only other mod on the Nexus: Scrollwriting in Skyrim. In all seriousness, though, I made this plugin primarily to make scrolls I wrote viable. So I think the two mods are good complements for each other.

This mod edits the base data for multiple scrolls and will require a merged patch (there's a tutorial on the Nexus tes5edit page) with mods that change the weight, value, display name, or other data of those scrolls. This mod is probably completely incompatible with other mods that edit the magnitude of scrolls, but that's ok because you shouldn't need two.

Thanks to hobo1137 and osmaawn for pointing out the mistakes in the plugin