It’s no exaggeration to say that for metalheads of a certain disposition, Voivod arethe band of the original thrash era. The reasons for such a seemingly bizarre school of thought are laid bare on Build Your Weapons, a not-particularly timely but undeniably absorbing compilation of highlights from the three albums the Canadians made for Noise Records in the 80s. Nearly 30 years on, the ingenuity and perversity driving the likes of Korgull The Exterminator, Ravenous Medicine and Brain Scan are still startling. Voivod used thrash as a starting point, but their perspective was skewed and at times they sounded like psychedelic warlords from another dimension. In fact, they still often do. The quickest way to sum up this double-disc affair is this: buy the actual albums, you skinflint. A deluxe edition of 1988’s Dimension Hätross is imminent, but assuming that there is still a point to these things, the music contained here is so dementedly exhilarating and vital that it defies cynicism about the need to package it in this way.