So, I like to collect spells (and magic items, and monsters, and sub-classes, and sub-races, ect., ect., ect.). This gives me some variety on loot to hand out, and opponents for my players to face. It also gives me quite a list of spells to pull from.
When I do write up a new spell (or pull one from some other source), this gives me the hassle to have to decide what spell list(s) the new spell will have to go on. In the past, when I’ve assigned the spell to the appropriate lists, I had to update my Google Docs file for that classes spell list to account for the new spell. In my spell list doc, I hyperlink it to the appropriate spell in my Drive. So out of laziness, and to save myself some work, I’ve come up with this solution.
You gain new spells as you raise in levels like in the Player’s Handbook, but can only choose from spells that are on your class’s spell list. If you want to learn a spell not on your class’s spell list, you need to do Spell Research as a downtime activity.
With Spell Research you can learn a spell that is on another class’s spell list, or a new spell from another source. This is more for my own campaign than for others, so feel free to disallow this part. In my game if your wizard wants to learn bless, or your druid fireball, that’s fine by me.
A spellcaster of 5th level or higher may use spell research to gain access to spells that he does not have access to from scrolls, spellbooks, or (if a divine spellcaster) his deity. Spell research costs 1,000gp, and takes two weeks of research, per level of the spell. A cantrip takes two weeks and costs 1,000 gp.
The DC to research a spell equals 10 + the level of the spell you are researching. You get to add your spell attack bonus to the roll. The research DC for a cantrip is 10.
Example: Pyro is an 8th level sorcerer researching wall of bones, a 4th level spell. It will take 8 weeks and cost 4,000gp, and has a DC of 14. With his +7 spell attack bonus, he only needs to roll a 7 or better to succeed.
A spellcaster may also use spell research to create a new spell. The spellcaster must describe in detail the kind of spell he wants to create, and the effects it will have. The DM will then determine if the spell can be created, and if so what the spell level will be. The spellcaster must be capable of casting spells of the spell level the potential new spell will be; otherwise he must wait until he attains a high enough level to research and cast the spell.
A spellcaster can only research a spell if he can still learn spells of that level. A cleric or other divine caster can only research a spell with the permission of his deity (DM’s discretion). The deity will usually remove a spell of the same level from the cleric’s spell list in exchange for granting the new spell.
To research a spell, a spellcaster must have access to a library. Wizard’s guilds and major temples often will provide their wizards and clerics access to such a library. If a spellcaster wishes to compile his own library, a minimum of 4,000gp must be invested to allow research on 1st level spells. For each subsequent spell level to be researched, another 2,000gp must be invested.
Having an exceptionally large library aids research. For every 10,000 gp of value above the minimum required for the spell, the spellcaster receives a +1 bonus on his magic research roll (up to a maximum +3 bonus).
Every time a wizard successfully researches a spell, 10% of the gold spent for that effect is added to his library value, reflecting the value of books purchased, notes, and annotations made during research.
Authoritative tomes or rare books found as treasure might provide an additional bonus to research specific spells or types of spells.