Two evenings of ad hoc combinations of improvising musicians drawn from a pool of ten – a format devised by guitarist Derek Bailey in the 1970s. Compered by Stewart Lee, the pool comprises Khabat Abas, Julia Brüssel, John Butcher, Teresa Hackel, Charles Hayward, Petra Heller, Pat Thomas, Matt Wand, Alex Ward and Mark Wastell. London Cafe Oto, 15–16 December, £30/pass, £20–£18/evening.