Donnelly comes fresh from a series of breakout shows in the UK capital this month, ahead of a reissue of her debut EP Thrush Metal via Secretly Canadian while Prass (pictured above) will be playing tracks from her sophomore album The Future and the Past, due for 1 June release. So-hype-right-now-it's-ridiculous London rapper Jimothy Lacoste is also added along with fireband singer/songwriter Nadine Shah.

As part of the 20th Anniversary celebrations and before heading on his North American tour, Ólafur Arnalds will present two special previews of his three-piano show at Þjóðleikhúsið, the National Theatre of Iceland. Erased Tapes-signed Högni also plays a show at the National Theatre, complete with choir and string section.

Among the homegrown talent added are Sturla Atlas Emmsjé Gauti and Sóley. This year’s winners of Músíktilraunir (Iceland’s very own Battle of The Bands) Ateria appear alongside finalists Ljósfari and Mórókóar.

More than 50 acts from 15 countries are joining the festival's 20th Anniversary edition which features already announced artists Fever Ray, Blood Orange and Alma.

The festival, which runs from 7-10 November, also welcomes musical innovators Kat Frankie, Mari Kalkun, Mueverloreina, Tawiah and Vaz to the line-up as part of the Keychange initiative.

The full list of international acts added today is: Crumb, Danny & The Veetos, EivØR, Fieh, Injury Reserve, Jimothy Lacoste, Kat Frankie, Mueveloreina, Nadine Shah, Nanook, Natalie Prass, Off Bloom, Philip Emilio, Rizan Said, Stella Donnelly, Surma, Tamino, Taiwah, Tuvaband and Vaz. The new announcements from Iceland include: Afk, Andartak, Beebee And The Bluebirds, Berndsen, Birgir, Birnir, DaÐI Freyr, Einarindra, Emmsjé Gauti, Future Figment, Glerakur, Hinemoa, Högni, Joey Christ, Karitas, Kef LavÍk, Kött Grá Pjé, Mighty Bear, Mr. Silla, Munstur, ÓLafur Arnalds, Ring Of Gyges, Rythmatik, Shakes, Sóley, Sturla Atlas, Sura, Svala, Vio

Tickets and more information is over at icelandairwaves.is.