Re: 3e-style Psionics using 4e-style tools
 

That will get you a functional psionics system; but that’s all it will get you. I’m trying for something a little more ambitious than that.

Re: 3e-style Psionics using 4e-style tools
 

No psionic system will be perfect unless its perfectly suited for the setting, something that is completely dependant on setting assumptions and therefore even a more ambitous system will break down if its not operating under the same assumptions.

In sum, when making a system to be generalized, I tend to be ambitious only when it concerns to adapting a system to my campaign world. Otherwise ill be constantly reinventing the wheel.

Re: 3e-style Psionics using 4e-style tools
 

The key lies in making it adaptable.

Re: 3e-style Psionics using 4e-style tools
 

I don't follow this point. If Y is truly a prereq, then it's necessary to know Y well, as it's fundamental to doing X, or even a subcomponent. It doesn't make sense to default a prereq from the main skill. For instance, if Algebra is a prereq of Calculus, you don't just study calculus and somehow get Algebra = Calculus - 4 as a side effect. You'd have to learn enough Algebra first to even learn Calculus. Prereqs should be either a minimum enabling level for later skills, or perhaps might cap the dependent skills.

If Y isn't truly a prereq, but some other related application of the power, then X and Y are separate skills. TK Punch doesn't really help TK Lockpicking, no matter how good at punching you get.

If the skills are closely related but not really a prereq, they'd be Techniques of some common base skill. Campfire and Fireball might both be Techniques of Create Fire (or Pyrokinesis, if you prefer). (The degenerate case here is naming one of the Techniques the same as the base skill, which is why I avoided calling them "Create Fire" and "Fireball".) This method will be analogous to Ritual Magic, with some number of specialized skills based on some core, with likely several core skills matching the base power Advantages.

Re: 3e-style Psionics using 4e-style tools
 

Perhaps it would help us understand your system better if you can give examples of a psychic skill set, the Potency advantage involved, and how that translates into performing psychic feats. For example, the Telekinesis set could have Lift, Levitate, Deflect, Throw, all governed by TK Potency [X/lv]. Lift takes a modifier for the weight of object moved, the distance to the target, speed of motion, etc.

Re: 3e-style Psionics using 4e-style tools
 

Using absolutely no actual term of Psionics, I'm going to see if I understand this correctly, because your ideas from another thread intrigue me;

Foo_Ad is the potency advantage. It is worth X pts per level. What really hugely matters here is if the trait is exponential, logarithmic, or flat increases.

Foo_Skill1 is an example skill. It is priced exactly as a normal skill and is merely here to act as a skill. It describes something you can already do due to Foo_Ad. It is nothing more than Climbing or Acrobatics; something a normal person could do with or without any points in it.

Reading your OP, it sounds like Foo_Ad might also be a bad talent. I don't think it should in anyway affect the skill. It's literally there to be your 'ST'.

Buying Foo_Ad at level 1 and Foo_Skill1 at IQ+10 gives us a weak and narrow but precise character. Buying Foo_Ad at lvl10 and Foo_Skill1 at IQ-1 gives us a powerful but narrow and hard to control power. To branch out, you'd either get more skills or advantages.

Since Foo_Ad isn't really a talent but ST for purposes of whatever skills it offers, then all we have to do is figure out which each level gives us.

Now to look at actual psionic abilities, Psychokinesis is quite broad. In Psionic Powers, it points out you need a minimum 31 points to have it all, not including the side powers you can add on. That pushes the value of the first level up to 40 or even 50 pts. Mind, some traits don't line up well with levels properly, and some aren't openended, making high levels less useful or putting a cap on how many you can buy. I'd call it roughly 40pts/lvl (and make that the maximum, maybe ESP and Teleportation are worth that much).

So, making each level of Potency 20, 30, or 40pts sounds fair (with a note on limitations for having only one power or a few of the trait, such that some can give a -80%). Then just describe what each level gets you. The first level is somewhere around 1d of damage, a BL of 0.2, a range of X, etc.

Separate from all that, there can be Talents or Wildcard skills that encompass the skills you get. As for skill difficulty itself, I like the idea.

Re: 3e-style Psionics using 4e-style tools
 

More or less, yes. My “Potency 0” notes are there to potentially blur the line a bit, by suggesting a (minor) variant where Potency isn’t strictly necessary. But yes; in theory, Potency is what enables everything to work, while the Skills (and Perks) “merely” denote which uses of the Potency you’ve figured out. And yes; the progression of the various Parameters is what’s going to make or break this system.

I think it’s worth noting that despite Potency not adding to the skills, it serves a role very similar to Magery; and as such, should be customizable in many of the same ways.

Essentially true. In practice, I like the notion that particularly skilled use of your power lets you eke out a more effective result, which is where the “margin of success” business comes into play; but that has the unintended consequence of giving you a means of comparing Talents to Potency. So maybe I should drop that and just go with the notion that a Critical Success gives you something extra.

…and this is where the Magical Scope Parameters or Effect Modifiers from Thaumatology and Ritual Path Magic factor in: they, or something like them, tell you what each level of Potency gives you.

Yes. You also have the option to switch to the Ritual Magic learning scheme for the skills, with a single core skill (e.g., Thaumatology or Ritual Path Magic), one or more Path skills, and individual uses of the power as Techniques.