Published from 2007 to 2008, Sinestro Corps War was a Green Lantern crossover event by Geoff Johns and artists including Ethan Van Sciver and Ivan Reis. The story follows Sinestro's assembly of his own corps wielding yellow power rings fueled by fear, mirroring the Green Lantern Corps' willpower-based rings.
Recruiting the universe's most terrifying beings, including the Anti-Monitor, Superboy-Prime, and the Cyborg Superman, Sinestro launches a devastating assault on Oa and Earth. The conflict forces the Guardians to rewrite the Book of Oa, authorizing Green Lanterns to use lethal force.
The event introduced the prophecy of the Blackest Night and established the full emotional spectrum of Lantern Corps.