From http://www.merriam-webster.com/dictionary/exploit

1ex·ploit

noun\ˈek-ˌsplȯit, ik-ˈ\: an exciting act or action


2ex·ploit

verb\ik-ˈsplȯit, ˈek-ˌ\: to get value or use from (something)
: to use (someone or something) in a way that helps you unfairly

When we say exploit, we use it as a noun but what we really mean to say is 'to use a bug in the game in a way that helps you unfairly' so it should be "exploit a bug in the game".

2bug

noun
Definition of BUG

2
: an unexpected defect, fault, flaw, or imperfection <the software was full of bugs>



The problem is that since there is no official description of how the game is supposed to work, unless the developers of some one that works for uCool states that a game behavior is an exploit, it is up to the player to decide if is a bug. There are some game behaviors where it is obvious that it was not intended to work that way, but in other cases it is not so clear. specially since come of the aspects of the game are counter-intuitive, like the way that Flavious power is related to the number of stars he has vs the number of star of the opponent and not on the attack power vs the the opponent defenses like all the other heroes.