This is the sequel to "CANDY" on the album, following a lot of the same strategies in the production. We will get to "CANDY" eventually, but it has something I would call "ethereal reggeaton" which just fucking eats. "DIABLO" is on that same vein, at least for sections of it. The song opens with a twinkling piano that genuinely sounds like you're in outer space. This is then backed by Rosalia's gorgeous delivery. It then SMACKS you with a TikTok / Alvin and The Chipmunks / nightcore vocal production on Rosalia and a reggeaton beat. Then, the reggeaton production blends for a small section with the twinkling piano from the start, with Rosalia's voice going back to normal. It then does another switch up later, where James Blake sings a guest verse, with a completely edited vocal that Blake is known for.
All of that is to say that the song is structured in opposites. There's not a single switch in the song that does not directly oppose the previous. You've got this ethereal moment at the start, then manic reggeaton, and so on. It's wild. What's interesting is that Rosalia says the album is split into two sides (MOTO and MAMI) and I really thought this song was smacked in the middle of both, but according to the track list, this is a MAMI song. That side of the album has practically all the ballads, so it's just weird seeing it here.
Personally, I find the demonic bits to be a bit grating, but the song does indeed smack. I found myself returning to this album a lot after it came out, and this just wasn't one of my absolute favourites, but I never skipped it unlike other songs.