Magic scrolls are pieces of paper that have a spell attached to them. Created by the scribe command, they can be used either to remember or to cast the wizard spell scribed. Both of these uses remove the spell from the paper.
Unlike the hag stones commonly used by witches to store spells, any player with appropriate magical skill may use a scroll to cast the scribed spell.
Spells are dangerous things, and as such, scrolls require some magic skills to control safely.
Casting from scrolls
Determining which spell is inscribed upon a scroll or casting it both require a magic.items.scroll check to be passed, the difficulty of which is dependent on the size of the spell. Otherwise, casting is exactly the same as a wizard casting the same spell, including components and skill difficulties.
Explosions and Escapes
Moving a scroll into a container invokes a check to the mover's magic.spells.special skill, which is modified by the number of scrolls that container would then hold in its immediate capacity. A significant failure causes an explosion which can be significantly damaging, depending on the number of scrolls involved. Lesser failure causes the scroll to escape and 'fly away', damaging the mover and giving a -1 or -2 intelligence hit. This, of course, lowers the relevant bonus, making subsequent scroll movement checks more likely to fail. If your intelligence goes down enough, you will fall unconscious. The Restore ritual can return your intelligence to normal.
This skillcheck occurs when you log in, as well (because the scrolls get recreated and then moved into your inventory), making it a bad idea to log out with too many scrolls in your inventory/containers without sufficient skills.
Keeping scrolls contained
Keeping all scrolls in containers all the time seems to make it easier to reduce the possibility of spells escaping from scrolls as long as there is absolutely no scroll carried (uncontained) in your inventory at any times.
To keep your scrolls contained and actually get a scroll you need to move all the scrolls everywhere in your inventory out of it, except possibly one container. To do so you can drop the containers, put them in furniture/vaults or give it to someone else. Only get them back when there is no longer any scroll carried.
That way, when you handle a scroll (just taking it out of a container counts) you have a low total amount of scrolls on your person.
All scrolls on your person count against your skills when a scroll tries to explode or escape.