Trent Reznor has led the charge in crafting a sinister soundtrack for the impending war with the machines. His mechanistic synth clatter has inspired electronic music's most enigmatic tinkerers (Aphex Twin, Skrillex) to find salvation in earth-rumbling cacophony, and alt-metal and trip-hop's most adventurous navigators (Deftones, Portishead) to expose the tension in all the dark spaces in between.