How do you create a CE Exp Bomb?

Get a low star CE, preferably 1* or 2*, Limit break it to increase the level cap, then feed it all the CEs that you can burn.

That's basically all there is to a CE bomb.

Just to elaborate on the previous answer. This works because CEs store experience, so if you feed X exp to a CE then feed that CE to another one it will give X extra exp. Since feeding 1* or 2* CEs costs less qp it is most efficient to feed a bunch of 1* or 2* CEs to eachother, then feed those to the CEs you actually want to level.

This is the guide I've been using since day 1

https://imgur.com/a/lYaqf