The crew could be walking around, and all of a sudden they come across a huge cult! (they all have the same outfit and everything, i think i know what the outfit should be...
) And they try to join them, not knowing its a cult! And they make them do crazy stuff, but they end up not being able to join anyways...
Of COURSE theyll need a hood, so:
Either Saradomin or Zamorak or HAM hood
Robes: I dunno where to go from here.... (except for HAM robes)
Matching amulet (holy symbol, unholy symbol, or HAM logo)
...The leader will have a staff, possibly slayer staff (its preferred, as it looks like an elder's staff