"Bad, yes. It is very bad." Celena replied. "The Septarian in the Present with Death in the Past is a harbinger of great destruction. Someone with the great desire for death and destruction is prepared to shift the paradigm, and the form of the threat you face is… unknown, beyond what the cards have so far said. And it is called the Present, not the Future." She continued. "It comes soon."
Okay, commented this in the Discord, may as well post it here, too.
Desire for death and destruction fits Negaduck, who seems to have awareness of magic stuff and may be working towards something paradigm altering. Moon connection is very vague, however.
It does not fit the Collector, who just wants to have fun (death and destruction being stuff that just kinda happen when he has fun, but not the goal), although the little bastard has a strong Moon connection. Belos has the desire for death and destruction, but no real Moon connection beyond the Eclipse involved in his draining spell.
Toffee has desire, but no Moon connection. Demona has the desire, a vague moon connection and a high willingness to flip the board if she feels like it will give her an advantage.
Lunaris is an insecure little bastard, but his moonvasion was more about proving the superiority of planet Moon than about causing death of destruction. Still one of the better suspects.
And, I guess, there is also the Core, from Amphibia. Given the events of the series finale, there is a strong Moon connection, there is a desire for death and destruction, there is no respect/interest for the masquerades in Earth and Amphibia stuff seems to have started showing up in Los Angeles.