They only knew the process of what had happened.
First came a violent tremor so intense that one might think they had been directly hit by large-caliber artillery, followed by a burst of light that streaked across the sky and darted into Ymir, imbued with rainbow light. It was only when the crew reported back that they realized "Durandal" had escaped after destroying the hull of the ship.
Why? What exactly had occurred? They were clueless. Though they were eager to rush into Ymir, the deadly rainbow hues reminded them that stepping over the threshold was a forbiddance akin to death.
There lay a beautiful hell, where the flesh and blood may absolutely not tread; even if one was clad in spellwork and heavy armor, they would still vanish without a trace the moment they plunged in. Only extraordinary beings and the chosen could linger amidst the rainbow's hues. Powerless, the people could only gaze upon that cruel beauty and silently wait for the disaster to pass.
"Roland..."