When I enter your dreams, the nightmare begins.
Actually, this is just a story about traveling through infinite worlds and getting up to mischief along the way.
For example: planting the seeds of Waaaagh in WOW, then using the opportunity to spread some philosophy; modifying the ReC 300 Heroes series into a chaotic free-for-all; F/A modifying the 21 Heroic Spirits into a Call of Duty: Modern Warfare; turning the Marvel universe upside down with a modified free-for-all between its heroes; RWBY monsters... tormenting people, uh, hunters (on hiatus); stirring up trouble in Super God Academy (ongoing).
"I'm going to stir things up! I'm going to cause trouble!" by Xia Nuo
PS (2): I already have a completed 1.5-million-word novel, Those Transmigrators from Back Then. The author's integrity is guaranteed, so please trust me.