Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

The multiplier tweaks might work, I'll have to crunch the numbers -- I do like the idea of just tweaking the spell costs as to messing with the Safe Threshold numbers. I had considered not using the multipliers at all and imposing a penalty to successfully casting the spells instead - but I worried that some spells would get a lot cheaper than I intended.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

I wouldn't recommend altering the safe threshold table any. However, if you want to triple the effectiveness of a given level, you can mostly do so by redefining what a 'Greater Effect' is or how it impacts energy costs. Maybe Greater Effects don't alter energy costs at all - they just make the ritual more dangerous in some way, such as making it so any failure is treated as a critical failure (any quirk is a botch) unless you take a penalty to the skill roll.

Body of Shadow is so expensive because it has 2 Greater Effects in it, making it cost 5 times as much as normal - by altering the Greater Effect definition, you can make it a measly 70 energy.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

As others have pointed out, a effective skill of 15 is...kind of low. A serious charm creator probably has a high-end Workspace Kit, maybe a place of power, grimoires for commonly created spells, and an apprentice or two that can help. Depending on your campaign setting, you may want to decide what is and isn't a Greater effect to offset the cost of some rituals (as has been previously suggested); let me also suggest you take Pyramid #3/66: The Laws of Magic for toying around with RPM in general.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

13 is about right for a Professional Skill, but by Professional Skill we're talking about the sort of skill that you use to make job rolls or that NPCs have for whatever services they provide. Note that the skill level calculated includes the +4 for unrushed, unthreatened actions

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

You never get a time bonus for casting magic. Magic is a dangerous business, you're better off playing with your dad's chainsaw instead.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

Right. That's one of the major reasons why 15 is the base 'professional skill' level for a mage - they don't get positive TDMs for 'unrushed, unthreatened' use.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

Again, I think the OP is overlooking the bonuses you can acquire for grimoires, places of power, workspace kits, and so on.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

Question that occurs to me:

Would a charm creator need separate grimoires for the "cast" and the "charm/conditional" versions of a ritual?

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

No, not overlooking them. But am observing that needing to be kitted out to the gills to safely attempt Body of Shadows and other spells I consider more mid-ranged isn't proving to be as compatible with my goals as I would like. I can fluff out grimoires to be something other than tomes and workplace kits is a little to academic sounding for the type of sorcery I am trying to force RPM to be, methinks.

The suggestion proving to be most useful so far is to revisit the Lesser/Greater effects and be a little more friendly on what is a Lesser spell and instead of using cost multipliers I'm going to impose penalties to the casting rolls instead. This will make the channeling of energy for larger spells a little friendlier while making it more likely that casters attempting spells beyond their ability will fail the casting portion.

Re: [RPM] High Energy Cost spells (Example Body of Shadow)
 

Negative. The added Lesser Control Magic effect to create a charm is the equivalent of saran wrap, but for spells. It keeps it fresh and portable. That said, a grimoire that can only be used to create charms might be worth half as much just like casters can purchase formularies for potions (see p. 29 of GURPS Thaumatology: Ritual Path Magic)

That's what I did when I wanted certain spells to be commonplace and others not to be. Just don't increase the cost of spells willy-nilly or require extra spell effects for a single effect - otherwise your players will get grumpy.