Rick Prime, Evil Morty and others in “Unfinished Business”

If you're seeing this, you're me - except, you know, less. But you acted like you were better, so I killed your beloved Diane. Partly to devastate you, mostly so I only have to record one message. Some of you may have noticed that it's not just your Diane that's gone. She’s also been erased from every universe across infinity. And you might be wondering why.

I'd rather hear how.

Diane was wiped from all existence by the Weapon Too Cool for a Name...

The Omega Device.

...known to inferiors as the Omega Device.

I heard the name from an inferior.