Pre-ret Beyonder is going to slowly increase his kill-o-meter until one is dead.
Who goes first?
Highest feats for both, and the Beyonder has the ability to destroy them both.
His unkillableness doesn't stem from the fact that he literally can't die due to lack of death in the universe though and more from the fact that he's just damn beastly.
I've always wondered what would happen if Darkseid tried to use the OE on Pariah. He would be constantly teleported away while the beams would constantly follow him forever.