It's hard to believe that Lamb of God has been issuing its staunch metal grooves for two solid decades without faltering. Yet as this comprehensive package asserts, that's exactly the case. Looking to celebrate those many miles and malicious riffs, the band offers up Hourglass, an impressive triple-disc set spanning its career.

Kicking off with “The Underground Years,” the disc opens with the band's — then dubbed Burn the Priest — Legion/Prosthetic Records years, clearly its rawest, most aggressive and enthusiastic incarnation. With 13 of the band’s personal favourite tracks from that era, the disc is an enjoyable if not altogether smooth ride.

Running over to the equally impacting but slightly more refined second disc, “The Epic Years,” well, it's rather obvious what's going on here: Thirteen more tunes pulled from the band's current and most successful era. However, its with the third CD, “The Vault,” that Hourglass truly shines, thanks to 18 rare and/or previously unreleased songs culled from bonus tracks, rehearsal demos and even pre-Burn the Priest works. From “We Die Alone” through “More Time to Kill,” “Suffering Bastard” and “Preaching to the Converted,” the band's youthful vigour and barbaric thrust is both engaging and communicable. Essentially, while Hourglass is really little more than a Greatest Hits package with some unearthed gems tacked on for good measure, the overall vicious energy and passion makes it an essential addition to any Lamb of God fan's catalogue.