"You can run, but how are you gonna hide?" said Helga, a smile gracing her face for the first time during this whole fight.
That was when Midas realised he had been duped. She had lured him close enough to her so that when she activated this thing, Midas would have no time to make some distance between them.
Midas even wondered if her inability to properly fight back was a ruse as well, but he decided it was probably not the case. This was not some brilliant thing she was exposing, it was a surefire way to end the fight. This was her nuclear bomb.
Midas was sure that after all this time, she was almost drained of Energy and now as she activated that thing, she was merely doing a last ditch effort. If it worked she would win and get what she wanted. If not, she would lose and probably find a way to run away. That was her plan.