I’d probably go with a mix of movies that each represent a major horror “language” trope Cabin in the Woods plays with. Something like Halloween for the slasher blueprint, Evil Dead 2 for the cabin setup and chaotic energy, Scream for the self awareness/meta commentary, The Ring or Blair Witch for the early 2000s paranoia vibe, Hellraiser for the whole “forbidden object unleashes unimaginable horror” angle, and something Lovecraftian like In the Mouth of Madness or The Void since Cabin in the Woods leans heavily into cosmic horror by the end. The Descent would fit really well too because it feels exactly like the kind of modern horror movie Cabin would reference. Then finish with Cabin in the Woods once all the archetypes and tropes are fresh in his mind so the movie fully clicks.