"They cancelled Jabberwocky tomorrow, so I'm gonna hang out here and try to get laid." Mark Kozelek from Sun Kil Moon makes for an unlikely comic between his misty wails about first loves, elderly mothers and friends lost to the state penitentiary, but his point is good. Transport much of the impressive bill from the ill-fated London Jabberwocky shindig to an idyllic vale in the Brecon Beacons, douse in alternative science and Wicker Man schtick, and you have Green Man, the perfect hang-out zone for the discerning indie pagan.
Compact and smartly programmed, the 12th edition rewards rambling; you're never far from a new favourite band or 10. On Friday alone you're swept along by the synth rock of Teleman (imagine a 3D-printed Alt-J), the canyon bombast of Augustines, and Mac DeMarco closing his set of slack trucker funk pop by falling backwards into the crowd from 20ft up a tent strut. If Mariam the Believer's impression of Yoko Ono undergoing jazz childbirth in the Walled Garden gets too much, simply wander to the Far Out tent, where the enthralling psych rockers Toy are essentially the Horrors if a large cargo crate of tunes marked "ship to: Echo & The Bunnymen" landed on them.
Saturday is a deluge of delights. The War on Drugs masterfully merge the Cars, Dire Straits and Neil Young into a very modern AOR. Hamilton Leithauser, the Walkmen singer, rasps torch songs of purest gravel despite his air of desolation being shattered by swarms of toddlers chasing bubbles through the crowd. Hordes of hypnotised converts stagger from the Far Out tent after witnessing Fat White Family, those notorious flingers of filth, chanting to the ancients and playing soiled rock'n'roll like pervert Buddy Hollys or the B-69s. And Sunday finds Real Estate drenching country and western in thick reverb.
All three main stage headliners prove magical, too. Beirut are a gaggle of suave, brass-parping boffins transforming Glanusk Park into the world's biggest bierhalle with pint-smashing sway-alongs like A Sunday Smile and Elephant Gun. Mercury Rev play their grandiose 1998 classic Deserter's Songs in full, the puckish singer Jonathan Donahue conducting the album's crescendos and firing the most cataclysmic chords from his fingers like a space-rock warlock.
Even among such refined company, the long-lost no-fi folk legends Neutral Milk Hotel stand out, closing Sunday night with a ramshackle, acid-warped party of singing saw, trombone, banjo, accordion, uilleann pipe and Satan's fuzziest acoustic guitar. Holland, 1945, Song Against Sex and Ghost prompt euphoric bouncing worship, and with The King of Carrot Flowers – alt-folk's Bohemian Rhapsody – the valleys sing. When they burn the mystical green man at midnight, a ball of flames finale seems apt – after all, the summer won't get better than this.
