To find out what stairs you can currently challenge someone in, first go to the Main Stairs Page, then click on "Show your stairs only" link. The ones in BOLD are ones you can make a challenge in. .
Vikings: I understand what you are saying, in that case they would have to be an exception to the rule, but they would still be in-active. There has to be some sort of rule set i think. Maybe they have to challenge if someone is one step below them & available. Something would have to be there though to check they still are an active player on Brainking. Until Fencer gives us his views or what he intends to do with the Stairs(if anything) all we can do is come up with ideas lol