can someone recommend me some underrated horror movie

Trick 'r Treat (2007) slips under radars lately because it's from the mid-00's, which isn't old enough to be a classic but not new enough to be a big thing.

Climax (2016) is an arthouse horror film about a group of dancers who take acid. It's filled with artistic shots, crazy camera angles, long no-cut scenes, and more. It's also in French. It's directed by Gaspar Noe, and like all of his films, it's really not super accessible, but it's probably the single-most disturbing film I've ever seen. Some of the splatter films/torture porns are probably up there, too, but this one is intense.