Hmm thats a bit too complicated for my genius level brain. I was thinking more of a simple elegant system:

No more than 99 people can enter and the object of the challenge is to enter and then after a 5 minute waiting for people to enter, everyone starts to crawl on their stomachs untill either they reach the finish line which is the same distance from valkurm dunes to lets say the cloister of flames or untill a random mob aggros you and you die and have the chance to start over again.

Now this would be a true endgame challenge.