Okay, a bit of an exaggeration, but there IS a cameo of Mr. Destructoid in Eternity's Child. To see him, go to the Ruined Forest level. As the level loads, you will see an elevator going up a line of coins to the left of the beginning platform. You won't be able to jump on the elevator the first time around, but wait for it to come down. This will take quite a while, but be patient. Get on it once you get the chance and go up.
At the top, there's a couple platforms and winged heart baddies, but clear those and you'll see what I took a screenshot of here.
Also, protip: The she-Knuckles fairy thing's right click charge attack, when fully charged, will knock a winged heart enemy out of the sky without making it burst into smaller enemies. That should help a little bit if you're bothered by the pesky things.
LOOK WHO CAME: