Which class are you using? Anyways, because i do not know your class, all i can tell you is to re-spec until something works and do not save after you re spec so you don't waste money. (hint, as long as the bug has 8 focus, I think, he can heal)
-if you are a bio max dissrupt,break and wound if you want get some attacks too but the starting attacks should do well -if you are a hydro max flash freeze,mind freeze and regulate get some attacks too -if you are a psycho try traumatize and confinement if those dont work try to find your own way
As a hydro: MF+FF, nuff said. As a psycho: Traumatize 2/2, applied each 3 turns. Nuff said. As a bio: A full set of ComboX or Disrupt 4 times and Break. Let Dux do all the healing.
Either take away his focus, stun him, don't let him use any focus moves, or mix those three up. On heroic mode without training battles you can't just try to outdo the healing with damage...