Hmmm I see your point. It could have an after effect of reducing your energy regen rate by 50%-100% for the next 5 seconds or so.
There are other things you could "take away" other than just flat health/energy. For example:
- it could reduce/take away health/regen rate for a while (as I just mentioned),
- reduced armor,
- affect your ability to accelerate,
- affect your ability to maintain speed (eats at your speed instead of health or energy),
- mausgang's storage idea(requires a charge up which requires time and effort to charge it up, and needs to be used relatively soon after),
- exponentially increasing health/regen loss (ex. a boost that has a short cd, but the quicker you use it right after another the more health it takes from you),
- depletes ammo (ex. a core that unloads all your bullets/rockets at once, in random directions),
- restricts movement (like Volt's anchor idea)
- reduced damage output
- temporary support role (reduced damage in 1v1 fights, increased damage when in team fights (enemy needs to have been damaged by a team member/team member's proximity to you and the enemy, etc, although there are other possibilities)
- any combination of these
Clearly there are more possibilities, I just mentioned what I gave up with off the top of my head in two minutes. Personally, I think its much easier to think of some sort of disadvantage for a core than an advantage, so I sometimes overlook mentioning one because I can usually just pick one out of a hat. Thanks for pointing that out however
