My understanding of using the Time Stop battle item is that it is supposed to drain 100% of enemy mana, but it doesn’t seem to be doing that. Around 3:15 Central Standard time, I used one in the Legendary event. The enemies turns reset to max, and I saw red text that said “Resetting”. However, the mana did not move down at all, and the enemies used their special attack next turn. Here is a screen shot.
If you do need to replay that Stage, Time Stops can work very well, you just need to make sure to fire one before Red Hood goes off, or kill all of the Minions first.