In case you've been wondering how to fix your negative levels.
You buy the scrolls from Rathmus who resides in the (badly marked on the map) field hospital. Rathmus gives you a hint that he can read scrolls for you while you are at the camp. The operative phrase is "at the camp". The devs saved themselves some work because if Rathmus reading scrolls for you only worked within the field hospital tent, they would have to devise a way to have you move your party members to that tent, or a way to have Rathmus move to the party member in question.
Instead they went with the solution that saves them work, but is harder for the player to figure out. You can cast any scroll from your belt that can be targeted at a friendly, and as long as you've bought this scroll from Rathmus, it auto-succeeds and the combat log says Rathmus has cast it:
As an added bonus of confusing the player, the scroll still says "Can be used with skill check", even though this isn't true in this case. And the game already knows it's not true, because Rathmus-bought scrolls are the only ones that will be cast by him (I've tested it).
So the devs have a flag for "scroll bought by Rathmus" but they don't use it to display a different text in the scroll tooltip.