This whole plan started when Shiller's car was sabotaged by the Talons on his way to take a holiday.
Shiller always considered himself to be very tolerant. This tolerance refers to his impartial attitude towards every personality.
It doesn't mean that personalities with negative traits should always be locked away. Since the aggressive Moonlight Shiller was allowed to get some air in Marvel, it's only fair that the personality representing morbidity in Shiller should also be let out for a while in DC, right?
Of course, initially, Shiller didn't make this decision. He simply planned to keep everyone busy with legit work while dealing with the Owl, and by everyone, he meant the source of various petty conflicts in Gotham—Batman.
Everything Shiller told Batman was true. He indeed came to Metropolis, and his first stop for investigation there was Anderson Psychiatric Hospital.
The reason wasn't anything special. It was purely due to an occupational hazard; he wanted to see if Metropolis's psychiatric hospital had anything that Arkham Mental Hospital could learn from.
The manner in which he infiltrated was quite similar to Batman's, so he also ended up in Isabel's room and learned the truth behind the hospital from Isabel's letter.
After discovering this, Shiller knew that the opportunity to let some dangerous personalities get some fresh air had arrived.
After releasing the morbid Shiller, the latter turned everyone related to this secret experiment, including the bank manager, the owner of Parlo Company, the owner of Snow Mountain Company, and the woman in charge of this experiment base, Eliza, into the victims of a serial murder.
While committing the crime, Shiller left a clue to steer the investigation in the first case— the janitor and the cleaning agent.
The scenes captured in the surveillance footage were all carefully planned by him. First, a blurry figure in a janitor's uniform appeared in the rooftop surveillance footage, guiding Batman to investigate the janitor's case. From there, the investigation would inevitably lead to the Snow Mountain Cleaning Company.
Batman would then discover that if someone wanted to use janitors to transport dead bodies, they would have to use the large box the cleaners used.
With Batman's wisdom, he would definitely notice that there is a single loophole in using such a plastic box for transporting bodies: the smell.
If they wanted to investigate the smell of the cleaning agent used, they would inevitably trace it back to the supplier of Snow Mountain Cleaning Company, the Pyro Chemical Material Production Co., Ltd.
On completing the investigation into the Snow Mountain Cleaning Company and the Parlo Company, combined with the clues from the bank manager's investigation, the key pieces of information related to the three main figures would be collected. With the combined wisdom of Batman and Lex, it wouldn't be hard to find out about the illicit dealings between these three.
The financial statements of these companies wouldn't reflect anything strange. These owls had been lurking here for too long, so such deceptive practices were second nature to them. The only remaining clue was the Parlo Company's move to renovate the West Suburb Psychiatric Hospital.
Indeed, this was very odd because to renovate this psychiatric hospital, a lot of protocols had to be followed. Compared to this, there were plenty of other places in the suburbs of Metropolis. Even if they were adamant about choosing the west suburb, there were better options. Batman would surely realize that the Parlo Company didn't choose this hospital randomly.
After guiding Batman, Shiller had another trail to set up, which was aimed at Kira. He learned from the letter that a KGB agent could have been killed by the owl. Shiller knew that if Kira got a clue, she couldn't ignore it and would definitely come to investigate.
However, Shiller didn't have any definitive clues to lure Kira here. He had intended to start his own investigation once Kira took action, but surprisingly, Kira's response came quickly, almost simultaneously.
In Shiller's plan, there was initially no room for Constantine and Angela.
Both of them being absent wouldn't have made a significant difference to the plan anyway. In the end, Shiller would have either died in the hands of the owl and the KGB or in the building explosion resulting from their fight. There was fundamentally no difference between the two outcomes.
Shiller had employed this tactic in Marvel: with his death, Iron Man and Captain America teamed up for a united front and the global demon gods were in deep trouble. If he died again in DC, his friends would again present a united front and this could spell doom for the Owls.
More importantly, as long as Batman was involved, during Shiller's stay in the hospital, he would definitely go after the Owl and therefore wouldn't have time to go back to Gotham to squabble with Lex and Clark.
In this way, without the owl, without the three people who fight all the time, and without the aftershock generated from various incidents, Shiller could finally have a peaceful holiday.
Of course, just like all his previous plans, besides the main objective, there were several other goals as well.
For instance, making the owl pay a small price for sabotaging his car; deceiving Batman's emotions to make him realize that fighting is wrong; and using the opportunity of faking his own death to ask Death in this world why he couldn't die in the other world.
Through the dream god, Shiller learned that all the members of the Endless Family knew about him fleeing this world. This fact could easily be concealed from common people, but it was unrealistic to hide it from the Concept Gods. Hence, he planned to ask Death directly: What was so special about him? Why he couldn't die even when he wanted to?