Good news for fans of extreme music, as Hellfest returns to Clisson from Thursday, June 18 to Sunday, June 21, 2026. At this grand rite dedicated to metal, festival-goers flock to the Main Stages. But if you’re into death metal or progressive metal, head to the Altar stage, where a host of talented artists are on the bill. The Halo Effect, Napalm Death, Igorrr... Here’s our pick of five acts you shouldn’t miss this summer on the Altar at Hellfest.