As I noted in another recent thread, there are things about Realms of Power: Magic that bug me, despite it being one of my favorite books for the line so far. Having had another day to think, I've begun to put together some houserules to make things work in a way that feels more natural to me. Constructive comments are welcome.
First: Balancing Qualities, Virtues, and Experience
I've noticed some odd things about experience values and costs, and these are my house rules to balance them. These are largely based on the premise that a minor virtue is worth 50 experience points, and a quality is roughly equal to a minor virtue in most cases.
So! First thing. One way to spend Improved Powers is one mastery point to five experience points in Concentration, Penetration, or Finesse. Improved Powers grants five mastery points. It seems fair, then, to double the experience value of a mastery point, though the other effects of mastery points should probably be unchanged. This coincidentally means that Improved Abilities and Improved Powers are the same if focused wholly on improving those three abilities.
Another issue. Gaining Qualities from Transformation appears to be too easy. Specifically, 10 XP to get a Minor Quality can earn you 50 XP. The solution seems to be to multiply all the XP values in this section by 5. Sure, it's slow to gain qualities, then, but that seems fair: gaining virtues and virtue-like things should be a challenge. This makes a Mystery-like transformation (a quality and a balancing inferiority) cost 25 XP (minor) or 75 XP (major), but the experience investment end-result still ends up being similar to a Mystery Cult member's expenditure in seasons and investment in Cult Lore.
I'm not sure requiring someone to spend 50 experience points for a single point of Might is fair, but I'm also not sure a single point of Might is equivalent to a minor virtue. Realms of Power: Infernal has a minor virtue giving 2 points of Might, so perhaps improving Might by 1 should be a new option that costs only 25 experience, and the Might-altering qualities (still costing 50 experience) would have doubled effects.
Second: Vis Consumption
The rules are unclear on whether consuming vis for purposes other than fighting Acclimation can trigger a Vis Consumption roll. Having looked at the table, though, it seems more interesting than dangerous, and even potentially beneficial, so I've decided to have it count any vis consumption toward countering Acclimation; if enough is consumed at ANY point in the season, the roll is immediately made. To be fair to the high Might beings with a billion botch dice, though, I'm tempted to make the botch effects temporary (perhaps they heal at a rate of one minor inferiority per season, or something.)
An issue's come up in another thread; the new rules make training familiars harder than ever. It didn't cost vis in the past, and now it does. For a compromise, I'm going to assume that the familiar bond allows the magus (and only the magus) to teach the familiar without Might-based penalty. Should the familiar want to practice on its own, or be trained by someone it's not bonded to, the vis cost will still be required. I figure if a magus wants to spend seasons improving a familiar rather than improving himself, that's fair enough, and he shouldn't have to jump through too many hoops to do it.
Fourth: Preternatural Tethers
As written, the math for preternatural tethers is slightly broken. It's not TOO bad, since the error only shows up in one particular case: if you started with multiple low-level tethers, say five strength 1s, your preternatural tether level is 5. If you gain a single tether of more than double the other tethers -- strength 3 or 4 -- your total tether level actually DROPS to that level. So a covenant with many Might 10 magical cats would actually become LESS magical if a Might 40 dragon moved in or something. This doesn't fit, to me.
One possibility is to just take the strongest tether + the number of weaker tethers, without requiring that those weaker tethers be at least half strength. Another is to only count the strongest tether. And another is to count the strongest tether and add one if there's at one or more weaker tethers of at least half strength.
That's it for now. If more houserule things or ideas come up, I'll try to post them here. I hope someone's interested, or has input!