Be resting in the same room as the Solar Altar at 6:00am, be sure to go early so you are there in time.
WARNING: Entire zone is CPK and no-recall, do not take items you are not prepared to lose. The Solar Altar room does fire damage, so be sure to watch your health.
For experiencing the start of a new day in such unusual fashion, the Powers have granted thee a Mark. You have been granted The Mark of Dawn! You gain 56 practices!
Addendum: Went in with a form on 9/28/11. Only I got the mark. It's randomly granted to only one person resting in the room. --Sanger