Can’t wait for this year’s AFTERSHOCK Festival? You may get repreive slightly earlier, thanks to a just-announced pre-party event at Slipknot’s Scream Park (4909 Auburn Boulevard).

Rockers Hell or Highwater will headline the party—and the band has also been added to the Saturday AFTERSHOCK lineup—on Friday, October 23 from 7 p.m. to midnight. Tickets? Free, but on a first-come, first-served basis, and you must already have a ticket to AFTERSHOCK. The party will include more live music and food trucks, plus, partygoers can roam the extremely creepy haunted houses at Slipknot’s Scream Park for a discounted $15.

Tickets are still on sale for the two-day AFTERSHOCK, with Slipknot, Faith No More, Deftones and Jane’s Addiction among the headliners. Look for updates about the official pre-party lineup and how to get tickets on AFTERSHOCK’S Facebook page.