Mythras/RQ6 really doesn't do a good enough job of explaining what to do with the tools they give you. Tuning MP regeneration is probably the biggest customization tool and they don't give enough examples. It's extremely hackable, but you're given a set of hand tools and asked to build a house.
...hmm, never thought of it that way, but I think you're right. The RQ6 magic system is basically a toolbox. Of course, it has enough bones that you could play it straight without much trouble. It's greatest feature though is that it's adaptable, and even though there are pages of suggestions for tool use, you need a fairly clear picture of the final product before you can begin to build.
Depending on how much editing power you want to give your players you can always just say "Regenerate X MP with an appropriate ritual" and let the player come up with something. You might want to set some guidelines like minimum time or expense.
...or come up with something for them. Either way, if you want that "idiosyncratic, unpredictable, and risky" S&S vibe, I think your stuck coming up with something different for each caster/spell/magical tradition.
I tend to really dislike the term "magic system"... ...it's thematically appropriate for each spell to be unique.
Exactly, as soon as you say "this is how magic works," you have lost the magic of it. In such a case, it seems almost futile to develop and detail the whole of the "magic of the Hyborian Age." You almost need to focus simply on the unique magical structures for each PC and NPC sorcerer that have a direct impact on the game/region you are running, developing new uniqueness as the PCs encounter them letting the other magics of the world remain in darkness.
Again, don't think of magic as physics ("I do X, I always get Y with no other or unpredictable consequences") but as a contract with an otherworldly power. In exchange for those MP, occasionally that entity you're entreating with is going to demand you do something. And if you refuse, he's not just going to stop giving you MP, he's going to eat you because fuck, he's not running a charity here. All that supernatural power running through a mortal frame might cause issues - maybe all your body hair falls out (sorcerors are always bald), or your nads shrivel up, or your body fat and muscle tissue gets consumed by the power until you're not much more than skin and bones. Maybe all food tastes like ashes, or the sorceror is consumed by lust he can never consummate (cf nads, shriveled) which explains why they're always kidnapping nubile young maidens.
Yes, but as a game, you can't really be too arbitrary with the consequences for PC sorcerers, can you? I mean, you don't want to just come out of the blue and tell a PC that his nads shriveled up due to a spell failure do you? You at least need a chart or something where you can point and say "these are the things that could happen to you if you take it too far" or something.
Just docking points from CON as each spell makes the sorceror older a la The Golden Voyage of Sinbad works.
Yes! Fantastic movie! and I love how it portrays sorcery! Eye of the Tiger too. Again though, CON docking as aging works great for a particular sorcerer, spell, or tradition, but you wouldn't want it as a blanket rule.