I was thinking a bit about my campaign world today, and how learning magic is based on finding lost records (spell books, scrolls, and such) rather than being taught. It got me to thinking what a magic scroll might look like, what it might say, and what kind of condition it might be in after lying around for 1300 or so years.
It first occurs to me that the odds of finding a complete scroll in good condition might be a rare thing. Successfully learning magic might require finding more than one copy of the same spell. This kind of ups the opportunity for leaving spells around to be discovered, as well as creates more reasons to go dungeon delving. So first, a chart for percentage of the scroll that is legible
2 ) 5% of the scroll is legible
3-5) 20% of the scroll is legible
6-8) 50% of the scroll is legible
9-11) 80% of the scroll is legible
12) 100% of the scroll is legible
Next comes a roll to see what portion of the scroll is missing. Roll 1d4
1) lower left
2) lower right
3) upper left
4) upper right
If a caster finds the duplicate spell, and it includes his missing corner, you check to see if he has the entire spell. For instance, if he was missing 20 percent in the lower left corner, and he finds 5 percent of the lower left corner, he is still missing 15 percent. If he finds any other corner, he isn't any better off than he was before.
Here's where it gets interesting. He can try to cast the spell with his partial scroll, but the chance for miscasting is high. First, he has to have over 50% of the scroll to even attempt the casting. Then his chance of actually casting a spell is equal to the percentage of scroll that he has. So if he has 85% of the scroll, he has an 85% chance of casting the spell. Roll 17 or higher on d20 and nothing happens.
He can't try again until he finds more of the missing pieces.
If he does cast a spell his chance to cast it correctly is also equal to the percentage of scroll he has. If he casts it incorrectly, roll on the following:
Misfire Results Roll d6
1)The "target" part of the spell is missing, and a random target is affected
2)The protection part of the spell is missing, and the caster is affected instead of the target
3)The "sphere of influence" part of the spell is missing, and he get the opposite of what he intended.
(water instead of fire, earth instead of air, harm instead of cure, attract instead of dispel, etc...)
4)The power level of the spell is missing, and the spell does half damage
5)The power level of the spell is missing, and the spell does double damage
6) Something completely unexpected happens. Roll randomly on your favorite spell chart, or choose an effect.
Once a spell is cast correctly, the spell caster will always be able to cast it correctly. (He will have been able to fill in the blanks with his educated guesses.) In standard Labyrinth Lord rules and similar, this assumes he was transcribing the scroll, and jotted down the correct information once he guessed what it was. If he was able to cast the spell but it mis-fired, he gets to roll the Misfire Results again each time he casts it until he gets it right.