The 3rd-scariest movie I've ever seen.

Rating: 9/10 (19 June 2018)

The scariest movie I've ever seen is Pet Sematary, directed by Mary Lambert.
I have temporarily blocked out the 2nd-scariest.
Hereditary is the third-scariest. Like Pet Sematary, there's an upsetting death of someone younger.
As noted by another reviewer, the last ten minutes diffuse the tension--slightly--but not enough to remove the overall impact of the film.
Ari Aster is a horror master and I will probably never see a horror film by him again. This film was psychologically upsetting without being excessively gory; Aster cares about his characters and, as such, knows how to torture them.
All technical elements are standout, but Colin Stetson's score really gets under your skin.
This movie gets nine stars out of ten. Do not see it. Unless, for whatever reason, you loved Pet Sematary, in which case, go wild.