what andy said is true and works fine, however on our server we set up HP right after GW. most of them its the best time and many of the top players are online to help defend the cities.
the top 4 arena players power down to hit each other in a system #4 takes 3rd, 2nd then first place and takes armor/runes off. then the new #4 hits 3, 2, 1 and so on. there is 4 rotations to make sure and after that they all power back up and agree on not hitting each other until after midnight