UMUR "On We Slay" is the second demo recording by US, Florida based technical death/thrash metal act R.A.V.A.G.E. The demo was independently released in 1987. Since the release of the August 1985 "Rotting in Hell" demo, lead guitarist Mark Schwartzberg has been added to the lineup, making R.A.V.A.G.E. a quartet on "On We Slay". Shortly after the release of the demo R.A.V.A.G.E. changed their name to Atheist.

The demo opens with "On They Slay", which would eventually be re-recorded and included on Atheist´s debut full-length studio album "Piece of Time" (Active Records, May 1990). The song is already fully developed and sounds more or less like the subsequent studio recording would. "Brain Damage" was also included on the "Rotting in Hell" demo, but appears here in a more intense, sharp, and raw sounding version. "Undefiled Wisdom" which closes the three track, 13:20 minutes long demo, is exclusive to this release, but parts of the song were used on other future material. I think the heavy riff after the opening part of the song is for example an early version of the heavy riff from the title track from "Piece of Time".

"On We Slay" features high level musical performances, including an angry and aggressive sounding Kelly Shaefer snarling hiw wrath at the state of the world. It´s also a relatively well produced release, although it´s certainly not a polished studio release. It´s still pretty raw, simple, and unpolished, but the rawness of the sound production suits the material well. A 3 - 3.5 star (65%) rating is warranted.