Can be used unupgraded to upgrade the best card in your hand, just giving you a little bit of extra output for the turn. You can think about it like a Defend+ or an Iron Wave almost, when it's being used like this. Or you can upgrade it and pair it with card draw to upgrade massive swathes of your deck at once. If you pair it with cards which generate energy, or which discount their cost when upgraded, this can give you massive increases in output immediately.
