Ahead of Comic-Con International in San Diego, things are getting bad for DC Entertainment…and that’s a good thing. As part of its cross-platform celebration of the villains of the DC Universe in 2013, the company has been highlighting bad guy-centric products this week including teasers for the incoming “Forever Evil” comics event and now a debut trailer for the documentary “Necessary Evil: Super-Villains of DC Comics.” Arriving on DVD October 25, “Necessary Evil” looks at the nemeses of DC in comics, TV and film with help from creators ranging from Geoff Johns and Jim Lee to hopeful “Dark Universe” director Guillermo del Toro. See the trailer in full below, and for those heading to San Diego, check out the “Necessary Evil” panel Thursday at 7:00 PM.