Arguably no artist was as instrumental in helping to reinvent and reestablish the San Francisco heavy metal scene -- formerly the unchallenged birth-place of thrash -- into one of the planet's most eclectic and unpredictable, than vocalist/guitarist Mike Scalzi -- a lynchpin of the community, both via his primary vehicle, The Lord Weird Slough Feg, and parallel involvement in cult favorites Hammers of Misfortune.

But, having abruptly announced his dissociation from Hammers, Scalzi appears fully focused on Slough Feg as he hasn't in years; and thus, the naming of the group's fifth album as Atavism signifies not only a renewed commitment to their career-long, classic metal orientation, but to the band itself.

And in classic Slough Feg fashion, Atavism's highest achievement lies in reaching back through the decades to revisit numerous, timeless metallic genres, then recasting them in a thoroughly modern, at times contrastingly avant-garde light.

New Wave of British Heavy Metal fire and economy pervade songs like "I Will Kill You/You Will Die" and "Agnostic Grunt"; regal Gaelic twin guitar harmonies lend a Thin Lizzy flavor to "Hiberno-Latin Invasion" and the lyrically apropos "Man out of Time"; dynamic, progressive metal pomp fuels the "Eumaeus the Swineheard"/"Curse of Athena" tandem; straightforward rock & roll surfaces in "Starport Blues"; and there are a few Iron Maiden-like instrumentals in "Portcullis" and "Climax of a Generation." What's more, for all their head-spinning variety, all of the above are united by the dazzling speed and technical proficiency of thrash, for yet another fitting tribute to Slough Feg's home base and its glorious past.

There's also a welcome departure provided by the title track's acoustic classical guitars, and, consistently brilliant six-string dueling waged between Scalzi and long-time partner-in-crime John Cobbett -- particularly on "Agony Slalom" and "Atavism II." Consider, at last, that much of the music is surprisingly immediate, regardless of its often challenging and oblique lyrics, and Atavism's biggest potential may be introducing new listeners to the world of Slough Feg, and related eclectic metal bands.