Supercharges add an interesting level of game play, and supercharges are quite appropriate to a superhero setting. The term supercharge, however, limits how they function. I recommend the term Secondary Powersource allows for the most flexibility. There are two mandatory features of SP's; how SP points (SPP) are gained, and how SP points are lost. The optional features are; stat bonuses due to SP points, overcharge bonuses at max SP, etc. Characters would mix and match these to create the effect they desire. Here are some examples:
Forcefield:
Gained: Slowly over time
Lost: Used as temporary hp over actual hp
Bonuses: Adds armor the higher SPP goes
Overcharge: At max SPP damage to melee attackers
Solar Powered
Gained: Quickly while standing in direct sunlight
Lost: Slowly while moving away from sunlight
Bonus: Bonus to damage and armor
Overcharge: Sunburst explosion
Shadow Eater
Gained: Standing in darkness
Lost: Used as manna to make abilities much more controlling
Energy Absorber
Gained: Take damage from energy sources
Lost: Used as manna to make abilities much more damaging
Overcharge: Next ability criticals at max damage
Rage
Gained: Take damage
Lost: Inflict damage, slowly overtime
Bonus: Armor, regeneration, speed, damage, crit level based on SPP level
Leech Mutant
Gained: Take or deal melee damage
Lost: On use, see below
Overcharge: Ability to transform into extremely powerful monstrous form
I think that's enough to give you an idea. Again, players would mix and match at the expense of XP or some other currency to create their own Secondary Powersource. This is based mostly on the variety of supercharges that Marvel Heroes has, but that system lacks the customization.
Such a feature existed in CoH in the guise of powers such as [url=http://paragonwiki.com/wiki/Dual_Blades#Build_Up]Build Up[/url] (and at least one [url=http://paragonwiki.com/wiki/Power_Mastery]ancillary power pool[/url]) and was the [url=http://paragonwiki.com/wiki/Inherent_Powers#Domination]dominator's[/url] and [url=http://paragonwiki.com/wiki/Inherent_Powers#Fury]brute's[/url] (and arguably the [url=http://paragonwiki.com/wiki/Inherent_Powers#Defiance]blaster's[/url])defining feature.
As with the weaknesses idea, I'd prefer that such things be part of the AT or power sets rather than having to play a min-maxing game during character creation, lest I find myself at a disadvantage later on.
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[font=Pristina][size=18][b]Hail Beard![/b][/size][/font]
Support [url=http://cityoftitans.com/comment/52149#comment-52149]trap clowns[/url] for CoT!
Yeah I agree with Darth Fez here: these are some interesting ideas that might be incorporated as part of certain ATs or Powersets but I don't think I'd like to see them become "bonus" min/maxable powers that anyone could take. This would pretty much lead to EVERYONE having some version of this because everyone would want something like this if they could have it. As AJSB said it's true that this kind of thing appears in comic books but it's also true that not EVERY superpowered person in comic books has this kind of ability, Thus it shouldn't be something that everyone has access to in CoT either.
CoH player from April 25, 2004 to November 30, 2012
[IMG=400x225]https://i.imgur.com/NHUthWM.jpeg[/IMG]
Lothic usually has good points about which things should be open powers, powerset powers, or basic game mechanics so as to avoid "mandatory" powers. There is nothing that kills customization more than powers or stats that supposedly anyone can have, but, in truth, everyone needs to have so as not to be "gimped" relative to everyone else who has it. The answer to this is often to "link" certain things to certain AT's or power sets so that they can't be widely abused and can be more easily balanced when necessary. This is why CoT is backing off from the "free form" building of Champions and instead doing the AT's of CoH, but with even more ability to diversify customization than CoH had. Still great options, but easier to balance and control.
It's impossible to totally avoid abuseable stats/powers--for example, just about everyone maxed their Defense at some point in CoH, and the fitness pool was pretty much mandatory till they just accepted it and gave it to everyone. But keeping this type of thing to a minimum is essential for good, fun, diverse gameplay and to allow people to focus on and follow their unique theme and concept and not have to worry too much about crippling themselves--which is critical in this type of "create your own character and story" game.
FIGHT EVIL! (or go cause trouble so the Heroes have something to do.)