CONTAINS SOME SPOILERS
By now we're well used to the main characters of quickie teen horror movies not just being thick as an extraordinarily large number of short planks, but eye-rollingly stupid to a near-suicidal degree. The old gag about "hot teenagers get stoned and play with a ouija board in the spooky old house at midnight" isn't a joke any more, it's practically a pitch for a studio franchise. Maybe we're just getting fed up with it down here on the ground, but in a world with four Sharknado movies the anti-idiot signals just aren't getting through.
Satanic is a prime example of dimwit cinema: two couples head to Los Angeles, either to watch a sitcom taping or en route to the Coachella Arts Festival (the script doesn't seem sure) but really they're in town to check out famous crime scenes such as the Sharon Tate residence (they've also specifically booked a hotel room that was the site of a notorious suicide). For no reason beyond idiocy they decide to follow the creepy owner of an occultist bookshop, where they promptly stumble upon what looks like a Satanic ritual...
It isn't a total disaster by any means: it's got a couple of nice moments and the Final Girl's fate is suitably grim and horrifying, and there's a weird timeloop dropped in towards the end for no obvious reason. But it's as forgettable and undistinguished as any one of a hundred low-budget horrors, and it can't get past the fact that the four main leads are so facepalm stupid as to render them impossible to empathise with. Missable in the extreme.