Sinestro "overstimulating" an informant to get information out of her with a "moonball." A real-life comparison would be intentionally injecting someone with heroin until they overdose.
Kanjar Ro's henchman getting sucked into space by a hole smaller than his waist, screaming all the way.
Boodikka suffocating Hal Jordan by tightening what is essentially a plastic bag around his whole body.
After the battery is destroyed, hundreds of rings start raining down. Sinestro casually points out that, without the battery or the Guardians to save them, the other Lanterns died in the vacuum of space.