After having tried to communicate, even battled them, the Young Gods eventually fell into some form of madness, but eventually realized that the Celestials wanted them to act on their own. Varua eventually had the insight that the Celestials were in fact Uni-Minds from entire planets, encased into armor.
They returned to Earth and created a giant armor in Madripoor, then Varua formed the Panhuman Uni-Mind, intending to put it in the armor, bringing the Celestial Terran to life, for him to take his place into the Fifth Host, and for humanity to unite and be taken to the next level. Madripoor was chosen for the "ascension" because of its rich and poor fractions rigid separation.
As all Madripoor inhabitants' consciousnesses were dragged into the Uni-Mind, neighboring countries were impacted and China threatened to use nuclear weapons, the Eternals of Olympia intervened, entering in conflict with the Youngs Gods, while the Druig-sent Legba went on a talk with Varua.
Manipulated by Legba in doubting her claims, Varua, formerly protected by a force field she was generating, was killed at the instant she lost enough faith in herself to lower her defenses, and the Young Gods' plans were thwarted.