The pack updates the whole roster of Doom 2/Freedoom with over 650 sound effects of the corresponding Doom: Eternal enemies, complete with footsteps (a Hideous Destructor feature) and adjusted frequency/volume of barks.
Arachnotron/TechnoSpider shares the firing sounds with the plasma gun, which was also updated—if that bothers you, either bring your own sound effects for weapons to complement this mod, or delete these definitions in sndinfo.Arachnotron.