Figuring out the precise limitations is tricky. Even something as outlandish as Sumaru resting on top of a space ship became true, but you could argue that rumor had the strength of generations of conspiracy theories backing it up.
In this case, everyone already believes that this boy is extremely dangerous, and with good reason from what I can tell. Given how threatening he is, you'd have to contend with existing perceptions.
But I think there are ways to work around it.
For instance, you could spread a rumor that anyone who wears a specific emblem is immune to his abilities. It worked for the Joker Curse.
Or you could spread a rumor that his powers are limited to nonexistent within Sumaru.
It might take some clever loopholes, but I don't think it's hopeless. You just have to come up with something and spread it in such a way that you don't draw his attention until it's in effect.
no subject
In this case, everyone already believes that this boy is extremely dangerous, and with good reason from what I can tell. Given how threatening he is, you'd have to contend with existing perceptions.
But I think there are ways to work around it.
For instance, you could spread a rumor that anyone who wears a specific emblem is immune to his abilities. It worked for the Joker Curse.
Or you could spread a rumor that his powers are limited to nonexistent within Sumaru.
It might take some clever loopholes, but I don't think it's hopeless. You just have to come up with something and spread it in such a way that you don't draw his attention until it's in effect.