to answer your earlier question about how a 'shadow magic' talent might be implemented in Echelon using HERO System:
Assuming, for the sake of conversation, a 20 Active Point limit and 10 Real Cost limit (so all powers must have at least -1 Limitations) per tier, Expert 'powers' would have an Active Point cap of 40 points and Real Cost limit of 20 points.
The spells you mention are probably Control Environment, HKA, and Telekinesis (with 'only works in shadow' limitation). As individual powers they could have 40 Active Points.
However, if you want to have 'shadow magic' be a combined thing, you might want to use a power framework. Because I'm applying things differently, where the cap is on the talent slot rather than a pool of points, it would probably be necessary to limit the framework cost to 40 Active Points and 20 Real Points.
An Elemental framework with three powers at 20 Active Points would have a total of 40 Active Points (consistent with the tier limit) and would have limitations. You could use all three at once (modulo power initiation) at full power.
With a Multipower, and assuming all three are flexible slots, could have an Active Point limit of 25 (n+3n/5 = 40; 8n = 200, n = 25 points in the pool) but you could only have 25 Active Points in use at once, spread across the three powers. Switching to fixed slots lets you get this to 30 Active Points, but you could only use one power at a time (unless you bought them at lower caps).
Variable Power Pool is probably not the best fit here, but could be done. 26 points in the pool, 13 for Control (but you'll probably need to reduce the pool because it's bigger than the Real Point limit and you can't put limitations on it). However, over time you could have anything that qualifies as 'shadow magic', swapping them in and out as circumstances (and limitations) allow. As I said, probably not the best fit for this purpose, but could be good elsewhere.
So, if you want biggest power, keep them as individual powers: Control Environment, HKA, and Telekinesis. That eats three talent slots, though. Or reduce their power by about half and put them in a framework, but pay only a single slot. Advantages and Limitations were not really explored much here because I'm doing this off the top of my head, the book is kind of bulky and not convenient at the moment.