Self powered scrolls
 

In this variant the writer determines before starting writing how many points of fatigue the scroll will provide towards the casting of the spell on the scroll. (Usually just the initial casting cost, but can include multiple turns of maint if desired.) The time to write the self-powered scroll is extended by one day (requiring another DX roll or the entire scroll is lost) for each point of fatigue it will provide towards the spell.

Re: Self powered scrolls
 

To accomplish the same, I just want to make them put the full Mana required for the desired duration into the Scroll, in one go, at the end. If it's between game sessions, success is to be assumed without rolling unless they are leaving for an adventure in a few days, then I'd make them roll (and waste the full Mana put into it, not just 1 ST for a missed spell -- then there might not be time to recover and try a do-over).

Imagine the party runs into combat as soon as they are underway, and the wizard can't help -- "Oh c'mon guys, I was up til dawn finishing an enchantment!" Actually had my own wizard face a similar situation in play once long ago. He barely recovered his last point of fatigue before heading into battle, barely squeaking through it. But the extra drama just made it more fun.

Re: Self powered scrolls
 

Any additional costs?


Imagining special inks and illuminations, maybe made with crushed gems.

Re: Self powered scrolls
 

Time and risk. Note that the success rate falls with every added day.