Basically, I remember reading a few chapters of this manga and now for the life of me, I can't remember the name. It had a highschool student main, and he had a male friend who I feel was pretty clueless? That kind of type? And he entered a "game" with a mirror version of his school.

There, he used poker (or something similar) to defeat... monsters? I want to say it was monsters. I feel like one of the cover images was him sitting in a throne type chair with a bunch of students around him. There was also a really elaborately designed character named Loki, I believe. I'm pretty sure it had some form of horror/gore to it.

I may be wrong, but Rex Fabula? I don't remember if the guy used poker, but I do remember his power had something to do with gambling. I also don't remember if there was any character named Loki, but I read it a long time ago so who knows.

I also don't remember if there were a lot of deaths, but I do remember there was a fair amount of blood. I'm probably wrong, but oh well.

That's it, thank you!!