So it all started when Citizen Dawn attacked Megalopolis. She had evidently been planning this attack for a while, so the first heroes on the scene, Absolute Zero, Tempest, Unity, and Wraith, were caught completely by surprise.
Dawn's initial strike force consisted of Citizens Hammer, Winter, and Truth, and as soon as Truth was dropped, Anvil came in to replace him. Through the whole battle, Dawn consistently had someone dealing damage to all the Heroes. As such, Unity was unable to field a single bot for more than a few moments. In the meantime, Absolute Zero couldn't find where he'd put his Isothermic Transducers or Focused Aperatures.
Still, it didn't take long for Dawn to resort to Merging With The Sun. Unfortunately, even this had been planned for. While impervious to damage, Dawn took the opportunity to fully heal herself. Then, just before becoming vulnerable again, Dawn took a Hostage, and fired off a Devastating Aurora, undoing all the work the heroes had managed to do.
The heroes managed to save the Hostage, but that simply made the people of Megalopolis overconfident that the villain would be defeated. As soon as the Hostage Situation was dealt with, the Paparazzi ran in to get interviews. Using the press as a distraction, Dawn's team struck down Unity and Absolute Zero, and Tempest fell not long after.
Wraith managed to hang on for a little bit longer, but by that time the result was a foregone conclusion, especially when she was slowed down by an unexpectid Traffic Pileup. Interestingly, she held out long enough for public transportation, in the form of a Monorail, to clear up the traffic.
The heroes defeated, Dawn took them prisoner and returned to Insula Primalis, hoping to turn them to her crusade. Well, except for Wraith. She was just taken. Being understandably upset at their comrades being taken, the rest of the Freedom Five decided to send in a rescue team. Legacy and Bunker were unable to go, though, so Tachyon went in leading Visionary, Fanatic, and Ra.
This time, Dawn was the one caught unawares. She still had Hammer and Truth protecting her, but this time Winter was replaced by Autumn, and at the very start of the battle, Truth tagged out for Dare. Before Dawn knew what was happening, her entire guard was down, and Visionary had seen to it that she wouldn't fire off a Devastating Aurora for a long, long time.
Still, Dawn had a few tricks up her sleeve. She quickly Merged With The Sun, and as soon as she did so, also began Channelling The Eclipse and ordering her troops to Return. It didn't take long for her invulnerability to run out, but before it did, Hammer and Truth both came back. Fanatic, just before Dawn became mortal again, went into a Dive, picking up Hammer and throwing him at Truth, knocking them both out. Tachyon then cut off Dawn's access to extra troops.
Even so, while invulnerable, Dawn had once again fully healed. The heroes, on the other hand, were almost defeated. They would have been, if Ra hadn't been using his Staff to ensure he had the strength to stand in the way of enough blows to keep the team alive. But just as Dawn's invincibility ran down, she got to that Devastating Aurora Visionary had delayed. Fanatic and Tachyon had had enough, though. Fanatic, a strong wind away from falling over, called down a Wrathful Retribution, while Tachyon unleashed three Lightspeed Barrages, between them defeating Dawn before she could do anything else. Their leader defeated, the remaining Citizens wandered off, no doubt to be eaten by the island's fauna.
End result: Visionary 2 HP, Fanatic 1 HP, Ra 2 HP, Tachyon 5 HP.