It looks like Mastodon’s new album, “Hushed And Grim” (out October 29), will feature a number of special guests. During an interview with Kerrang!, the group confirmed that Soundgarden’s Kim Thayil, Municipal Waste’s Dave Witte, Marcus King, João Nogueira, etc. will appear on the effort. Drummer/vocalist Brann Dailor said the following about the new record,…