Actually, a few months ago an actual spoiler rule was put in place; there's a single month after release in which spoiler tags are mandatory. As such, Shadow and Rush are, technically, a free-for-all now.

Once the month has transpired, warnings for lack of spoiler tags will not be given, but mods can still edit spoiler tags in if they feel like it; using spoiler tags of your own volition after the month period is simply a matter of courtesy.

EDIT: Oops, wrong topic.