Three Ghosts
"The test is simple. On the other side of this Undead forest, two of us will be waiting. The third one, that is me will be racing with you guys to that point. If anybody manages to beat me, they will be the candidate.
If no one beats me, then the person that came right after me will be the candidate.
If multiple people beat me, then a battle would decide who stays and who leaves.
And, a fair warning. The Undead forest is full of dangers, everything in that forest tries to kill you guys. The trees, the insects, the beasts, all of them are the creatures that are either undead or they feed on the death energy inside.
Even the plan growing under a tree might kill you, so be careful and we wouldn't be responsible for any of the deaths or dangers you might encounter. So, join in at your own risk."
With that, two of the three ghosts made their move, two minutes in and they can already faintly hear the sound of the battle.