Los Angeles-based Deathbomb Arc and Chicago's Hausu Mountain have both built up extensive, sprawling catalogs that embody the free-form spirit of the D.I.Y. underground, completely disregarding genre boundaries and notions of what's considered hip, trendy, or tasteful. DBA emerged in 1998 and has long been associated with fabled L.A. venue the Smell and the U.S. noise-rock scene, but they've also been strong supporters of abstract, anarchist hip-hop since the beginning, with acts like Death Grips, JPEGMAFIA, and clipping. all making early appearances on the label. Hausu Mountain is considerably younger, but in less than a decade, they've already issued more than a hundred releases, including spectral drones, jazzy chiptune, cosmic pop, jam band-adjacent rock, manic punk-rave, and too much more to list. The two labels linked up for the Arc Mountain compilation, which includes 12 collaborations between artists from their combined rosters. It leans heavily toward experimental hip-hop, especially during the first half. Fire-Toolz's shattered, sparkling beats collide with They Hate Change's playfully swaggering raps on opener "Scene!," then Japanese trio Dos Monos spit molten lava over RXM Reality's fractured bass during "April 11." SB the Moor & Dustin Wong's "A Stream of Advice" and Sarn & Mukqs' "Wicked Thoughts" are more paranoid, confessional poetry than raps, and there are a few stabs at playful, naïve pop, such as White Boy Scream & Fire-Toolz's "Air Friar" and Margot Padilla's "Good Boy (proud)," one of four tracks produced by Khaki Blazer (Moth Cock's Pat Modugno). While his collaborations with J. Fisher and Angry Blackmen are bleating, blown-out mutant rap, "The Reaction" (with Fielded) is more accessible trip-hop/R&B with lush vocals and dusty breakbeats that only seem slightly bent out of shape. The album's later tracks feel more like experimental soundclashes. George Chen, Cooling Prongs, and MrDougDoug set a babbling speech synthesis sequence to a hyperkinetic rhythm, and clipping.'s Jonathan Snipes, also a noted horror film composer, constructs a suspenseful, witch house-neighboring soundscape along with TALsounds and Fire-Toolz (yet again). The album is rounded out by a storm of blackened industrial noise from Strega Beata (formerly Lana Del Rabies) and Davey Harms (the biggest link between the two labels, with releases on DBA as Mincemeat or Tenspeed dating back to 2008). Like both labels, Arc Mountain can seem dissonant, erratic, and all over the place, but it all ties together as a reflection of a larger community of artists united by an unending drive for subversive creativity.