When a band is fixated on one particular subgenre of rock music, and more specifically, one specific style that was groundbreaking close to 40 years ago, unless the band learns to use those vintage sounds while forming a musical identity of their own, the “retro” gimmick will inevitably start to fade after a few albums. After their first two albums, Sweden’s Witchcraft was on such a precipice. Their much-ballyhooed 2004 self-titled debut was a hit among critics, its impeccable homage to the proto-doom metal of Black Sabbath and Pentagram, along with a production style that made these guys sound like they’d just arrived from 1970, attracting a loyal cult following on this side of the Atlantic. However, despite being an enjoyable album, 2005’s Firewood offered listeners little variation from what they’d already heard on the first disc. Witchcraft did the retro doom thing very well, but it was clear that the novelty aspect of the debut was already starting to wear thin. Album number three, though, has the foursome taking some very bold steps, and while their music is still firmly rooted in dense fog of late ‘60s and early ‘70s heavy rock, the mood’s been brightened considerably.

For such a seemingly formulaic band, The Alchemist is a quantum leap compared to their previous work. Like their immensely talented countrymen Dungen, Witchcraft has managed to infuse the new compositions with influences that bring more variety than just the same old pentatonic riffs played over and over, their songwriting having evolved to the point where this music sounds as fresh as it does old-school. And thanks to their best production yet (courtesy Tom Hakava), it all adds up to their most potent sounding album to date.

Witchcraft has always been outspoken in its devotion to Pentagram, with singer/guitarist Magnus Pelander even adopting the sober singing style of Pentagram’s Bobby Liebling. However, some listeners are unaware of just how indebted the band is to Roky Erickson and the 13th Floor Elevators as well, and it’s that late ‘60s psychedelic/garage sound that Erickson helped pioneer that elevates The Alchemist from the doom quagmire. That stylistic shift is immediately evident on the hard-charging “If Crimson Was Your Colour”, which is built around a palm-muted riff that hints at funk and is highlighted by searing, undistorted guitar solos and a wicked Farfisa organ run, while Pelander actually evokes folk singer Donovan in both phrasing and his lyrics, primly enunciating the enigmatic line, “If crimson was your colour / could your conscience bear your soul?”

“Walk Between the Lines” is straight-ahead Nuggets-era psychedelic rock, tastefully distorted riffs underscored by acoustic guitar, Pelander’s singing his most assured to date, strongly carrying melodies and managing to sound emotional, a far cry from his rather chilly approach on past records. With bongos adding an extra rhythmic edge underneath Fredrik Jansson’s backbeat, “Samaritan Burden” eschews bombast in favor of restraint, settling into a smooth, quiet groove midway through, the stupendous breakdown and startling outro, replete with acoustic and electric guitar flourishes, wood block, and vibra-slap, are reminiscent of Black Sabbath’s Volume 4 album. And speaking of which, that Sabbath/Pentagram influence that dominated the past two albums does still sprout up on this album from time to time, but nowhere as prominently as on “Hey Doctor”, during which Jansson channels Bill Ward, shifting from a dirge-like pace to a swinging 2/4 beat.

Doom, psychedelic, and folk mesh perfectly on the title track that concludes the record. An 11-minute, three-part suite, “The Alchemist Pt. 1/2/3” represents the closest Witchcraft has ever come to fully realizing its potential, bringing in all those styles from nearly four decades ago and forging their own identity with it. Whether it’s the sprightly, jarringly upbeat riff that opens the track, the dark, crawling riff that snakes around the chorus, the chiming guitar notes of the middle section, or the mellotron-backed folk interlude that follows, it’s simple progressive rock, but like Dungen’s recent body of work, it’s pulled off impeccably, with none of the stylistic shifts seeming contrived or arbitrary. It’s a crucial moment of brashness and confidence in Witchcraft’s career, musical alchemy in the truest sense. “I can blow your mind,” Pelander boldly sings at one point, and we sit on the edge of our seats, eager to find out where he’ll take us next.

• Multiple songs MySpace