Hello, in one of the last games in Powered Cube Draft I played on this account just now, I ran into the following situation:

• I had “Urza, Lord High Artificer” in play, and I used his ability to tap multiple creatures for blue mana

• I then tapped some of my lands for mana, and realized I had tapped for the wrong color

• I hit “Z” to undo the tapping of my lands, but this also deleted the blue mana generated by Urza from the pool. The creatures remained tapped however.

This of course wasted my entire turn. Hopefully this information is helpful!