King Gizzard & The Lizard Wizard are so free-ranging that the Melbourne shape-shifters usually devise a firm concept to corral their vision from album to album. Not so with their first-ever double LP, which began as a gathering of miscellany left over from previous writing sessions. Even that loose guiding theme fell away when more writing and recording ensued, resulting in an epic journey through King Gizz’s recent sweet spots. Opening with the 18-minute prog-punk odyssey “The Dripping Tap,” Omnium Gatherum weaves naturally through organ-driven hip-hop (“Sadie Sorceress”), eco-minded metal (“Gaia”), falsetto synth-funk (“Magenta Mountain”), and Krautrock-inspired wig-outs (“Evilest Man”). Such a whiplashing showcase of contrasts might sound extreme, but this particular double-decker is consistent and accessible enough to serve as a mid-career retrospective forged entirely from new material.