They're Allman Brothers from different mothers, so Gregg Allman and Warren Haynes are always there for each other when it counts -- including this year's Christmas Jam, which will mark the Haynes-curated festival's 25th anniversary with a pair of sets from Allman.

Allman is scheduled to play both nights of the 2013 Christmas Jam on Dec. 13 and 14 at the US Cellular Center in Asheville, N.C. He'll be keeping some pretty impressive company too: The lineup also includes Haynes, Gov't Mule, Widespread Panic, Grace Potter and the Nocturnals, Michael Franti, Keb' Mo', the Phil Lesh Quintet, the John Scofield Uberjam Band and more.

Billed as "One of the greatest and longest-running live concerts in the U.S.," Christmas Jam serves as a benefit for the Asheville Area Habitat for Humanity. Over the past 15 years, festival proceeds have helped 24 families become homeowners, leading Habitat for Humanity to name a street in a local subdivision 'Warren Haynes Drive.' This year, to mark the event's 25th anniversary, Christmas Jam is partnering with the Sierra Nevada Brewing Company to produce the special limited-edition Christmas Jam Session Ale, available throughout North Carolina and on tap at the festival.

Although VIP and travel packages are already sold out for this year's shows, a limited number of general admission tickets are still available. For pricing and availability, visit Ticketmaster.