Virtuoso progressive metal may not be en vogue, but the mighty Mastodon resolutely sticks to its guns (tusks?) on its latest, Emperor of Sand. It may sound like a sequel to Dune, but the record is actually an extended meditation on the trials of cancer, inspired by the experiences of friends and family members. While the subject matter may to weighty, the group approaches it with its usual array of heavy riffs and brutal technicality. Blues rockers Eagles of Death Metal and local instrumental metal trio Russian Circles open the show.