Please note this is a list so if you guys come up with any and leave some of the comments it doesn't have to be truly inconspicuous but if it's considered safe for the list I will edit and my spin on it dash or your spin on it if I can't do any better.
Cheat one : wish for a ball that you have absolute control over (from size to shape material)clarify very clearly that it's indestructible reacting to your very thoughts
I know I may sound like I'm being specific and that might be suspicious But what if you are too control what's in it in a world of the XP you have a sea of dragons in your ball
To Drown in fire water or even lightning at your leisure
Or what if you choose to make it into a pocket world you will never have to camp always have food on hand and even have an absolute defense
And with no limit to the size you could very well take a world for your own but I wouldn't suggest that unless that God pissed you off somehow
Less overpowered ways to use the power
Make the ballfield with a chemical and set it on fire
Technically not magic so not possible to counter with typical magic counters
Shadow ball Dash make a copy of your ball for more versatility like you could build a wall of balls and change the ship to a cube to have an indestructible shield or wall if you go the route of war
Reproduction of your favorite materials and foods with the changes you desire - still overpowered but less of a powered then the World egg idea
Teleportation ball - need I say anything else
Like a minato teleport to your ball that can teleport anywhere you desire or with anyone you desire
Size control- shrink your world ball to the size of an atom
There are probably more uses but you get the concept it hasn't even getting into the concept of replicating magic with your ball without having to worry about the anti-magic thing or the possibility of being countered-already said that one but that was really important