The mechanics seem a little vague to me.

Does it mean everyone has an individual hour glass that begins counting down when they enter?
Does an individual/group claim a mob as on a regular battlefield complete with drops only falling to the individual/group?
Will the zone have a max number of people who can be in it at the same time?

I have more questions but the other questions involve the answers to the above. Depending on how it's implemented, it could be a real cluster. But, please make it nothing like WoE.