As far as I remember (age makes the memory a bit faulty) I think challenges have always needed to be mutual in order to keep others from joining in. However, I think (see above) that challenges will lower the health damage when you die, even if it is not mutual.

Perhaps a god could sort this one out?

Orielle (old enough to have a faulty memory)

Written and shown unedited exactly as rendered by text based game bulletin board on Avalon Online RPG and by my hand on the 10th of Leaflost, in the year 1411.