The lineup has been revealed for this year's Knotfest event in Iowa. The festival will be held at Water Works Park in Des Moines, IA on September 21 and it will feature the following: Slipknot, Till Lindemann, Knocked Loose, Hatebreed, Poison The Well, GWAR, Vended, Dying Wish, Zulu, Twin Temple, Holy Wars, Swollen Teeth, Spine, and Dose. Tickets and VIP Passes will be available on May 3 via knotfestiowa.com. A pre-sale will also launch on April 30 at 10:00 a.m. CT.