Copying spells from the looted books of enemy magic users
by Blacky the BlackballI've always hated this mechanic. It means that as a DM, whenever I put an enemy magic user against the party (as a plot related bad guy or simply as an incidental NPC) I can't let that NPC have many spells that the PCs don't have because I know that by doing so I am giving the PCs those spells - and even if I don't, I know that the biggest treasure the party find will be his/her spell book because even with just duplicates of the PC spells it would still be worth a small fortune to sell to other magic users.
Yes, I realise that there are ways around this by having the spell book trapped or disguised or hidden and so on to prevent the PCs getting hold of it, but it feels way too contrived having to do that every time.
My solution to this was to co-opt the Weapon Mastery rules for learning spells. Now, magic users have to spend time and money being taught a spell using the same table (with the same time, cost and chance of success) that fighter types use to learn a new level of weapon mastery. I just mapped each level of spell into an equivalent "Student's mastery level", and the maximum level of spell that the teacher can cast is mapped onto the "Trainer's Knowledge" using the following simple conversion:
Trying to learn level 1-2 spell = Student knowledge of "None"
Trying to learn level 3-4 spell = Student knowledge of "Basic"
Trying to learn level 5-6 spell = Student knowledge of "Skilled"
Trying to learn level 7-8 spell = Student knowledge of "Expert"
Trying to learn level 9 spell = Student knowledge of "Master"
Master is 1st-4th level = Trainer Knowledge of "Basic"
Master is 5th-8th level = Trainer Knowledge of "Skilled"
Master is 9th-14th level = Trainer Knowledge of "Expert"
Master is 15th-20th level = Trainer Knowledge of "Master"
Master is 21st level or higher = Trainer Knowledge of "Grand Master"
So, for example, a magic user trying to learn Fireball (a 3rd level spell) from a 10th level teacher (who can use 5th level spells) will be the equivalent of a fighter with Basic sword mastery being taught by an Expert swordsman - i.e. it will take 2 weeks of study at a cost of 250gp per week and have a 70% chance of success.
Since high level magic users aren't that common, magic users can also do research to learn spells do their own as if they were a teacher one category worse than their actual level-based category. So if the magic user in the above example were 5th level, then trying to research Fireball for herself would be the equivalent of a fighter with Basic sword mastery being taught by a trainer with only Basic sword mastery - i.e. it will take 2 weeks of study at a cost of 250gp per week and have a 1% chance of success.