To ensure the repeatability of the battle from the 25th attempt, a "timer" program is used, which is launched on a virtual machine.
The timer allows you to stop the moment, which is great because the ability activates at that moment.
The use of this program is a nuance that I don't understand, but I accept. On the one hand, you can spend two hundred hours in virtual battles and suggest that the host do the same. This is one extreme. You can write a program that does everything for you and provides the final save. This is the other extreme. Choosing a middle ground that would satisfy everyone is very difficult, almost impossible.