Since Shiller returned to the Marvel World, he noticed something strange about the egg. For instance, the "thump-thump" heartbeat sound became more distinct, his mind-reading technique could sense some emotions emanating from inside of the egg, and there was a constant "gurgling" noise coming from within.
Shiller thought that the egg was about to hatch and was continuously pondering how he could handle it for maximum benefit.
However, after observing it for a few days, Shiller realized that something was off. The heartbeat was continual, and there was a consistent noise coming from inside of the shell, yet there was no sign of it hatching.
Moreover, as the vitality of the life form inside the egg grew, Shiller could feel its emotions more clearly - the brutality and insanity unique to Doomsday, which almost seemed to be spilling out.
Although he was unsure why the Doomsday from the DC Universe had become an egg, now that Shiller knew what it could be, he was certainly preparing to deal with this monster.
It's hard to kill Doomsday. Or, in the DC Universe, it's tough for him to be killed.
Just like the killer devil, Jason, is nearly immortal in the world of Friday the 13th, it's not because they are truly powerful enough to avoid death, but because of the universe's power. In their universe, they are destined to be immortal.
Within the American Comic World, the fourth wall convention always exists, so it could be understood that the scriptwriters of that universe designed Death to let Doomsday live. Hence, he naturally can't die.
However, if Death doesn't claim him in that universe, it doesn't mean the same is true in this one. In the DC World, Doomsday had the setting of being immortal. But when he came to Marvel World with Shiller, this setting was no longer valid.
Additionally, he bumped into Ultron's setting. Both of them had gone through numerous hardships, refused to die, and had grown stronger, causing more trouble for the protagonist team. Their setting was nearly the same. But as a local, Ultron obviously had higher placement.
Speaking of popularity, when two villains with the same setting appear in a universe, whoever is more popular will be the immortal one. Now, Doomsday coming to Marvel World is barely a crossover issue, whereas Ultron is a well-known villain who often appears in the main world's comics. It goes without saying who is more popular.
This is also why Shiller wanted to deal with Doomsday using the Marvel Universe.
Similarly, there are tricks to handling it. If he releases it, a fight is unavoidable. Shiller has to choose the battlefield, opponent, and method of death to ensure maximum gains.
As per Shiller's style, it will be an incredibly complicated plan, containing dozens of subplots, taking roundabout routes, eventually achieving the final goal.
Originally, that's how Shiller planned to proceed. But now, he has found a more efficient tactic with stronger gains.
Firstly, he summoned the Gray Mist. Then he brought out the umbrella imbued with Spirit of Curse. After that, he let the Gray Mist, with the Spirit of Curse from the umbrella, seep into the interior of the eggshell.
In simpler terms, the Gray Mist functioned as a syringe, and Spirit of Curse acted as a pesticide—an injection of a high-concentration pesticide—significantly weakened life activity inside the egg.
Previously, Shiller had experimented with the efficacy of the Spirit of Curse on Black Panther T'Challa. This Spirit of Curse, the same bloodline as Constantine, seemed to possess a unique deadly curse that left even Panther God Bast helpless.
Also, looking at the curse afflicted Black Panther, it stuck to his spirit and didn't cause any external wounds. It killed the spirit from the inside, which coincided with Constantine's style.
Gray Mist worked like the syringe, injecting the Spirit of Curse directly into the Doomsday inside the egg. This immediately quieted the heartbeat and emotions of the Doomsday inside.
However, even a very thin camel is still bigger than a horse. After the powerful initial effect, they seemed to enter a standoff. The Doomsday inside the egg was moving on minimal energy. No matter how much the Spirit of Curse attacked, it couldn't completely kill it.
At this time, Shiller brought out another trump card: the highly concentrated soul energy of Hydra, which he had once fed to the Spirit of Curse.
When he sold Hydra's soul to Mephisto, his commission was this concentrated soul energy. Earlier, when Shiller had fed it to the Spirit of Curse, it had been very eager to consume it. Now, when it needed to work, Shiller willingly gave it enough 'food'.
With the Gray Mist transmitting this energy to the Spirit of Curse until it was satiated, the Spirit of Curse became stronger. It began using that tremendous curse power to gradually erode Doomsday's spirit.
The Spirit of Curse needed time to absorb the energy, and to entirely destroy the last bit of the spirit also required time. Shiller had entered the world within the ring with his flesh and blood, causing him to be missing in the real world. Thus, he couldn't wait for the Spirit of Curse to complete the task here.
He left a part of Gray Mist to monitor the situation, then exited the world within the ring and returned to the actual world.
At this point, Ultron came calling. He led Shiller to the basement of the sanatorium, where machine tools had been assembled, along with piles of equipment that Shiller couldn't comprehend.