Azealia Banks, Heaven, London

“How you all enjoying that cotton candy?” Azealia Banks grins. No need to worry what that might be a euphemism for. The most gasped-over new rap talent on either side of the Atlantic is most literally talking about the fluffy fairground confectionery, being handed out free to fans at the side of the venue.

There's reason for a carnival atmosphere; this is her first big London headline show, after a month schlepping round the country on the NME Awards Tour, and details of her debut album, Broke with Expensive Taste, have been announced.

The intimidatingly confident young New Yorker could take things anywhere from tonight. When her DJ Cosmo ambles onstage and drops the Prodigy's "Out of Space", its a sign that her aim for now is to maintain the momentum of massive, filthy breakthrough YouTube track "212" while keeping her new internet fans on board for the aggressive, relentless rap style of older tracks like "Runnin'" by twisting things towards the ragey, ravey side of the dancefloor.

After greeting the audience with a casual confetti bomb, she starts with a technically dazzling bare rap over the simplest of beats and scratches, drawing out her territorial lines as the real deal. Her style is a harangue, a pauseless volley of rhymes aimed at a grinning, bouncing punchball of an audience. The initially excruciating "fashion, babes" spoken intro of recent track "Bambi" builds in bug-eyed intensity before collapsing into something goofily fantastic as it reaches its unhinged, bouncing, yelling climax. This and the hard acid house chords and vicious flow of "Liquorice" make clear that Azealia's not interested in being another Rihanna or Cassie, a singer pinned to a braindead chart-humping synth line; this is dance-rap done smart.

She teases with a sung verse of "212" before dropping that beat, the one she's going to have to ride if she's going to make good on this early exposure. Everyone goes bonkers. Tellingly, she dispenses with the chorus of Prodigy's "Firestarter" she usually sneaks in. She doesn't need it any more. She certainly knows how to throw a party. As everyone gobbles down that cotton candy, massive, expensive looking, wedding-style balloons cascade from the ceiling. On the face of it, Azealia will be bouncing long after they, and that hype, have deflated.