1805. Bomb
It took the experts decades, but they eventually prepared everything required for the mission. Noah had completed the experiments with his bomb, and King Elbas had found a way to stabilize the dimensional tunnels long enough to carry the entire group.
Noah's bomb didn't require much external energy. He mostly used his dark matter, so he absorbed fuel from the mansion only when his dantian approached an empty state.
The same didn't apply to King Elbas. The expert's task was arduous and required him to transform a frail dimensional tunnel into a passage that could lead a large platoon made of peak rank 8 existences through the void.
Noah only needed the weaker world to grow until it could withstand the experts' pressure. King Elbas' task required a superior enhancement since the dimensional tunnel had to continue to work once the group stepped inside it.