In this modern, gritty adaptation, "Episode 12" refers to the fourth episode of Season 2 (as the show has 8-episode seasons).
Option 1: Ben 10: Alien Force – "War of the Worlds: Part 1" [S2E12] War of the Worlds: Pt. 1
Professor Paradox and Azmuth return to Earth with a dire warning: the Highbreed invasion is imminent. In this modern, gritty adaptation, "Episode 12" refers