Crystal Castles, Roundhouse, London

Crystal Castles haven't always had the best reputation as a live band; short sets and habitual tardiness have seen to that. But at north London's Roundhouse, Alice Glass (the screaming banshee) and Ethan Kath (the digital wizard) sealed their reputation as a mesmerising stage act, offering their hordes of frenzied teenage fans and ultra-cool hipster admirers a perfectly constructed combination of tripped-out euphoria and menacing digipunk beats to rave to. From Kath's first digital pulse ("Fainting Spells") to Glass's final blood-curdling wail ("Yes/No"), they belted out infectious melodies and all-consuming beats in a brutal assault on the central nervous system. And, two years after their emergence from the Toronto underground with two eponymous albums, it's clear that the noisy duo have lost nothing of their violent zeal and electro exuberance.

Glass is straight out into the crowd as Kath's first pounding beats test the grade-II-listed venue's acoustics to their absolute limit. A more sensual "Courtship Dating" sends her back to the stage to regain her breath before a fireball of ear-piercing shrieks and convulsions ("Air War") catapult her into the crowd again. But not crowd-surfing; instead she's perfected the art of crowd-walking – hurling herself forward but upright into the crowd, trampling fans' heads, necks and arms as they reach out to grab their pulsating hero. And it's this energy and musical violence that make Crystal Castles more than just a simple synth band, and Glass more than just a frontwoman.

Kath's digital genius shouldn't be ignored (it's his sharp electronic missiles that keep the noisy two-piece grounded in near-reality) and Glass's vocals aren't all that fantastic, but her stage presence is consuming. Gazing through pulsating strobes, her fans are hooked, convinced she's morphed from a lo-fi electro-indie hero into a soon-to-be rock god. And it seems, at least for now, that she's learned to turn up on time too.