One of the most interesting periods of the Hero Wars is the Lunar decade of 1639-1648. A new mask, Invictus, becomes emperor after the set backs and defeats of Argenteus, Kazkurtum, and Renovus, and rapidly rebuilds the empire. Like Khosrow II or Ashurbanipal, brought the Lunar Empire to its greatest height in 1645 before presiding over its collapse in 1646-1648.
Did Invictus witness the Moonfall? Did he try to salvage the Lunar Empire afterwards?? No. Invictus ends up being completely destroyed by Sheng Seleris. The whole 1645-1655 period is one like the Twilight Period in the GPC.