The King in Yellow made sure to be at peak condition before traveling to the Eldritch Universe's nucleus.
Unlike the one in the Prima Universe, a natural cosmic formation protected the Eldritch Universe's nucleus. It was so strong that no one beneath Extreme Rank 9 could get anywhere near it, and even those at that level would find it hard to cross it.
Phantoms of all sorts of Eldritch powerhouses impregnated the cosmic formation, distorting reality. Luckily for the King in Yellow, he controlled the Karmic Space-Time Omega Law and understood the Law of Cause and Law of Effect, allowing him to see the path through it.
It was not easy, but the King in Yellow managed to enter the Eldritch Universe's nucleus, and what he saw in it shocked him to the core. There was nothing in it but two mini-universes containing white orbs with incredible power.