Oliver Heldens offers glimpse of Knife Party collaboration at Tomorrowland Oliver Heldens played out his elusive collaboration with Knife Party during his Tomorrowland set, which was first revealed in 2015. Related Posts: Tomorrowland to unveil rollercoaster at Belgium’s Plopsaland Tomorrowland New Year’s Eve sets from Major Lazer, Tchami, Martin Garrix, and more land on Apple Music