Push it push it push it! Alexis Krauss shouts at the beginning of Reign of Terror, and that’s exactly what she and Derek Miller do on their follow-up to Treats. Despite its in-the-red volume, {|Sleigh Bells|}’ debut was a fragile, almost alchemical blend of wispy melodies and crushingly heavy beats and riffs. How could they top an album that was already turned up to 11? By turning things up to 12: on Reign of Terror, the duo brings the nods to metal that added a headbanging thrust to Treats and to center stage. From the album’s name down to song titles like D.O.A. and Never Say Die, Krauss and Miller allude to metal’s flirtations with death, which makes a strange kind of sense: Treats was a blend of sounds that shouldn’t have worked but did, and changing that formula is riskier still. With Miller playing a shred and squeal-friendly Jackson USA Soloist and a slicker production, {|Reign of Terror|} makes Sleigh Bells’ debut sound downright quaint by comparison. The duo’s alchemy resurfaces on the songs that sound the most like Treats: on Crush, Krauss sounds like a revolutionary cheerleader toying with a captive enemy when she sings I’ve gotta crush you now; End of the Line echoes the Treats’ hit Rill Rill’s breathy pop poses; Leader of the Pack boasts a tooth-rottingly sweet melody; and Comeback Kid balances the album’s heaviness with humor and finesse. The band goes deeper into metal territory with the aptly fiery Demons, which sounds extra-vengeful with strutting fretwork and rapid-fire kickdrums.