Moving towards ars magicka definitive edition, there are virtues in various books that need to be updated to come in line with the errata done on Elemental Magic and Secondary Insight. @David_Chart
Hedge Magic, Revised:
- Elemental Magic: Like the hermetic version.
- Elemental Medicine + Philosophae + Theurgy: Minor virtue, or up the xp gained to half the medicine study total. Leaning towards the later.
TC&TC:
- Magian lineage (Major): This needs serious buffing. As written, the major version could be a minor virtue, in line with Faerie Blood (minor). Maybe 100% study total towards the two other abilities might work if we keep it as major? Or just drop it to minor and if you deem it necessary, remove the bonus to disease resistance (not that this ever comes up in game, so I'd keep it).
Realm of Power: Infernal
- Hermetic Sorcery: On the surface, it looks fine. In practice, this looks more or less useless as a major. RoP: I 124 already says you can substitute Rego for Summoning, Ablating, Binding, or Commanding. As such, unless you can learn one of the 4 arts more than twice as fast as you can learn Rego - the benefit to gain half as many experience points is not a benefit, it's a penalty to learning. How often is this going to happen? High quality sources might be gained with ablating... but you could just raise "an appropriate art" and be done with it, without having to divide by two, raising a skill you'll never use, since you'll substitute Rego which is going to have a higher score always. Unless you deal with high level infernalists that have high com, good teachers and agree to waste their time for you, this will almost never be better than a Rego tractatus, since you won't use the main skill anyway, only Rego. This is a minor virtue - only the vim xp is worth it, unless the errata decides that Summoning, Ablating, Binding, or Commanding stack with Rego.
Base book:
- Learn (Ability) from Mistakes: How many abilities are going to botch or fail by 1 so many times that players should expect to make up more than 50 xp into the skill if bought straight up, or an affinity over the length of the campaign? I think I can think of only one very munchkin edge case, which I'd probably be hostile to at my table. I've generalized this to apply to all abilities - and in an adventure-rich game (2-3 adventures a year, spanning 2-4 sessions each), it gave 50 xp over a decade of gaming, which is about 4 years' worth of studying books with book learner over the same period, and it doesn't apply to arts which tend to be more important to a magi than skills.