"Issa Nightmare on Elm Street, feel like Jason, Friday 13th"

When 21 Savage utters that line in the superbly-executed transition between his "My Choppa Hate N****s" and Offset's "Nightmare," it's abundantly clear which rapper plays which slasher flick villain in this Freddy Vs. Jason of a mixtape. Savage is Jason Vorhees, the masked, machete-wielding murderer from the Friday the 13th series. Beyond his noted affinity for the character, 21's rapping reflects Jason's approach to evil: straightforward, bullish, menacing, light on the chit-chat. Offset is Freddy Kruger, the more left-field killer whose blades are flashier and whose approach is more creative. When the two horror franchises linked up for a joint film, it fell flat. Surprisingly, 21 and Offset's crossover episode succeeds. 

The key here: Metro Boomin, the third name billed on the project but the only one who appears on every song. Having him on-board equates to a Freddy Vs. Jason with horror legend John Carpenter directing and scoring, which clearly wasn't the case for the 2003 film. Metro ensures that Without Warning stays short, sweet, and plentiful in its Halloween-themed thrills. 

The Halloween mixtape is somewhat of a newly-minted tradition, with A$AP Rocky's Live.Love.A$AP, Future's Monster, and Young Thug's Slime Season 2 (all fantastic in their own right) all arriving on the holiday in the past decade. Those tapes are all higher-stakes than Without Warning, but this one does take the cake on staying the most devoted to the holiday. Monster, also a Metro Boomin-filled offering, was a great occasion for Future to rediscover his savage side after a breakup and an album he didn't like, but it also contained one of his best, most open-hearted songs ever, "Codeine Crazy." Not very scary. 

Without Warning, for its part, is the rap equivalent of a slasher flick: gory, over-the-top, and a lot of fucking fun. Most of the horror vibe comes from Metro, who expertly throws in demented laughing, chainsaws, gunshots, wolf howls, creepy music boxes, and Rosemary's Baby-level haunting backing vocals as backing tracks to his instrumentals. And goddamn, those instrumentals. Big bells, eerie piano, reverby bass, and sci-fi synths set the tone, but the way he deploys them shows the most progress. There are no predictable build-ups, and the way he tailors the ins and outs of his beats to each rappers' flows and emphases is impeccable. 

21 and Offset also ramp up the fright factors in their respective approaches. 21's first collab with Metro, Savage Mode, could already pass for a Halloween-themed release (in fact, engineer Alex Tumay said he had a "horror flick" in mind while mixing it), so this is child's play for him. He compares himself to Kim Jong Il and Mad Dog, says he's going to open up a morgue, and of course, talks a lot about his guns. Offset, clearly the less experienced horror writer of the two, hangs by keeping things less melodic than usual and, at least for the majority of the time, out-rapping 21 (though he does rap the no-shit-Sherlock line, "Come in the middle of the night like it's a nightmare,", so it's not a complete blowout). When Travis $cott and Quavo appear on the first two songs, they're almost too cheerful. Without Warning's vibe is so well-curated, any step outside the lines stands out like a sore thumb, even if there's absolutely nothing wrong with the verse.

The one exception, a song that's barely creepy but too amazing to hold against any project that contains it, is Offset's "Ric Flair Drip." Goddamn is this thing hot. Everything just hits, from the way Metro's subtle, fast-paced beat knocks, to Offset's differently-paced rapping on both verses. It's easily the best solo turn by any Migo to date, and probably one of the best singles of 2017, if it even sees daylight as a single. 

As a pair, Offset and 21 don't have what you could accurately call "chemistry," but they don't clash nearly as much as you'd expect. Never trading bars or supplying ad-libs to each other, they mostly seem like they stumbled into the other's songs to lend guest verses, and then got the hell out of Dodge. They're nice foils to each other, murking their respective appearances with very different skill sets, but don't be surprised if they never link up again and never give themselves a corny, Bad Meets Evil-style nickname. The glue is Metro, a previous collaborator of both rappers who clearly had both skill sets in mind when constructing Without Warning

At this point, Metro could probably do a 30-minute tape with Lil B, Logic, and A Boogie Wit Da Hoodie and make it fire. He just keeps getting better. He's already survived a few waves of producer turnover in Atlanta, and especially on Without Warning, seems to be absorbing some tricks from the new generation of SoundCloud rap producers. Innovative, experimental, and pop-minded all at once, the still-young beatmaker has yet again leveled up, and don't be surprised if he does so again in 2018.