The dark aura didn't bother Knife. He knew Merwin was setting up to cause some real damage; but he believed he could finish this fight before those boosts could prove useful to the Houndoom.

While Merwin's thinking, Knife seemed to vanish. Using Feint Attack he managed to disappear for a brief moment, dashing forward to attack Merwin again. The blow would be weak; it's a Dark type attack, Merwin resisted those; but it closed the distance and he followed it up with a lunging Dual Chop.