Death does not use any curses. Indeed, those who die of curses come to her, but she does not use death to curse a person. Her authority may be great, but it does not include directly killing a life.
If death could casually kill, how could there be any living things left in these universes?
Death represents only death, not killing, and certainly not curses. The latter are merely actions whose consequences result in death. Death cannot actively control them.
Does there indeed exist a surefire death curse in the universe?
In Death's view, there does, for instance, an absolute lethal toxin for certain organisms exists within a universe. Once this toxin is contracted, death is inevitable.
From a mystical perspective, indeed, there are curses that can achieve a one hundred percent kill rate. There are various ways to release these curses. It could be cast by someone like a mage or a priest, or it could cling to an item.
However, such curses have a unique characteristic. Most of them are only effective within an individual universe. Once moved to another universe, where even the basic energy rules are different, these curses naturally become ineffective.
Yet, what Death saw was that, around every Spider Man, everyone who said to him, "With great power, comes great responsibility," had died.
Looking at these individual deaths, there was nothing wrong. Death could not possibly scrutinize every word said prior to each death, hence, when accepting these people, she did not detect a problem.
But when looked at collectively, these deaths resemble a curse: death follows uttering certain words. If this is genuinely a curse, then the entity casting the curse must be extremely powerful.
However, Death scoured the multiverse and found no trace of the curse. From a being who can freely view and traverse timelines, this seemed almost impossible.
If the curse truly exists, there must be a puppet master behind it, and, in order for the curse to affect Spider Man, this puppet master would definitely intersect with Spider Man and the people around him.
With a single glance, Death could discern all cause and effect relationships. Nevertheless, she did not discover any clue related to a curse within these relationships.
If not a curse, then what could it be?
Death could not find any connection between this sentence and death, which was unbelievable because she herself is Death, yet she could not find a relation to this sentence.
But the incident had already occurred. Shiller has died because he uttered the sentence. Therefore, if one wants Shiller to refrain from dying now, he must refrain from uttering the sentence.
As previously mentioned, the so-called multiverse is actually comprised of infinite individual universes. So why is it said to be infinite?
In Marvel's setting, every choice results in a possibility, and each possibility is a universe.
In simple terms, when you chose whether to drink milk for breakfast this morning, if you chose to drink milk, that would be an individual universe. If you chose not to drink milk, that would constitute another individual universe.
Even a fleeting thought would constitute a universe, a dream would also represent an individual universe.
Therefore, in the multiverse, there are infinite possibilities; outside of the individual universe, there is no emptiness, only infinite possible universes.
In the possible universe at the current moment, Shiller has already uttered the sentence and died. If Death wishes to reverse everything, she must return to the moment before Shiller uttered the sentence.
And then, prevent Shiller from saying that sentence, creating a new possibility, and use this new possibility to overwrite the present universe. If so, Shiller may not die.
For Death, it wasn't difficult to do this. She first returned to the moment when Shiller first uttered the sentence and then caused some distractions to divert Shiller's attention.
Having left the hospital, Shiller didn't have the time to tell Peter, "With great power, comes great responsibility," so naturally, he didn't speak those words.
But, just as Death was about to overlay the newly generated possible universe onto the existing one, she found Shiller in the new universe had disappeared.
That's right, vanished into thin air, and Death could not figure out where Shiller had gone.
Death was puzzled, then she thought that in the multiverse, there are special existences, once, and only once, known as "Singular".
If Shiller was a "Singular", then his sudden disappearance could be explained. Since they are "Singular", no matter how many individual universes there are, no matter how many possibilities, they can only exist once.
To conjure another entity out of thin air for a "Singular" is not impossible, but Death is not a creator god, just a concept god. She doesn't oversee that department and thus lacks the authority.
However, this failure did not make Death feel defeated. At this stage of events, whether Shiller dies or not is not important, the main thing is winning.
So, if it's impossible to create a possible universe where Shiller did not utter that sentence, then create a universe where Shiller does not exist at all, then overlay it onto the existing universe. If Shiller does not exist, then he won't die.