Saturday: A group that seems to thrive on challenge, Twin Cities hip-hop collective Doomtree traded in its wildly popular Blowout concerts at First Avenue for a one-day festival in meteorologically unpredictable early October at St. Paul’s majorly enjoyable minor-league ballpark — which it hopes will become another annual blowout. Surprises galore are in store, at least one of which we can tell you about: Rappers Dessa, Mike Mictlan, Sims, P.O.S. (pictured) and Cecil Otter are rehearsing with a live backing band just for the occasion. We also know who else is playing sets that day, including indie-rap innovators Aesop Rock with Rob Sonic, Open Mike Eagle and Shabazz Palaces, Los Angeles punks Trash Talk and local pals Aby Wolf, Anonymous Choir and Koo Koo Kanga Roo. (2-10 p.m. Sat. $35-$45. CHS Field, 360 N. Broadway, St. Paul.