I would make the upgraded one cost 3 
as well, and make it do +2/-2 instead of +2/-1.
Since this is a card that will be used with high hp creeps anyway (basilisk blood, stone form gargoyle, flying titan, you name it), this will still be powerful. It's actually like acceleration, but FASTER! =D
Also, I'm not a great fan of the upgraded name (Overboost). I guess I'd like Overdrive better.
I do very much like the name Acceleration, since it matches very nicely with gravity and momentum in providing that real physics feel to the element (and to the science feel of the game in general).
Well, I was thinking that before as well, but the idea behind Overboost vs. Acceleration is that it's better, not faster.
Overboost was something I sort of came up on the fly, so I'm open to changes.
Thesaurusing Acceleration got me Celerity, and I like the sound even though the meaning isn't exactly the same...
Anyone have a single word for describing going faster than the amount of energy that you're using should allow?
I mean with out using words like perpetual motion (deosn't match), Momentum (duh), and entropy (duh)?
That would warrant the +2/-1 and still seem like moving fasterish?
