I have a custom creature card in my cube. It’s a 0/4 with the text: “Rubblebelt Rioters gets +X/+0, where X is the greatest power among creatures.”
If it’s the only creature in play, it’s a 0/4. If it’s in play with a 1/1, then it’s a 1/4. Easy so far.
What happens if it’s the only creature in play and it has a +1/+1 counter on it? Is it a 1/5? Does it see that the greatest power is 1, so it gives itself +1/+0, then +2/+0, +4/+0 ad infinitum?
I don’t know of any real card with a similar static ability to check the rulings for.
Yes, sadly that’s not possible from my cube. Still, it’s the first time it’s come up in around three years of playing the cube so hopefully no-one tries this again haha