So on Friday night a few members of my group got together and we went over the 2.9 rules, with me explaining a lot to them (one of them had the PDF already), and together we collectively built a character (on a whiteboard, using random rolls).
During our discussion, we spitballed on a couple of potential abuses. Let me know if - per the RAW - the following could not be done:
For one of the character's power slots, he chooses Devitalization Ray. He chooses -10 CPs, so that it hits for 2d6.
He then takes the modifier Takes Time, such that it takes 100 years for the attack to work (for another -47.5 CP). He could even have it Accidentally Activate, Very Commonly (for -7.5), with an Impossible CL save to recover (for another -7.5), and have it so that a Breakdown is likely (for -15 more). Shoot, we'll even build in some Miscellaneous modifier, to make it completely useless (for -20). It could also be Obvious to a couple of extra senses (-5 more).
Then he sticks that Devitalization Ray in his back pocket, with no intention of ever using it (other than when it accidentally activates, commonly, but since it takes 100 years to fire, it can be immediately shut down again).
Haven't we just given the character 112.5 extra CPs to move to other Basic Characteristics and Abilities? Or to select new Abilities to add to the character, since they've got all of those extra points? And yes, I realize that there are BC and Ability Caps that will limit whatever we add. But isn't that still a major loophole?
[I want to add that this is something that neither I nor my players would ever do or even ask for; I only point this out for the benefit of preventing abuse by anyone who would choose to exploit the opportunities there]
I think the simplest solution to this problem would be to say that all Abilities need to have a final cost of at least 0 CP, at a minimum.