In a good roguelike tradition, there should be a separation between spoily and non-spoily topics. That's not important yet for JADE. but for ADOM it is. There are two things which can be done to this end. It'd be best to have both :)
1) have two forums, one for spoily, the other one for non-spoily topics
2) have a [ spoiler ] tag which will somehow hide the text, but allow to show it when needed.
Voted. I have seen this feature on some forums: the text in the tags would appear in some kind of a coloured area, invisible of course, and the text in the area has to be highlighted with the cursor to be able to read it.
Just install this official mod (assuming you own a vBulletin license). It's configurable, but the generic status is exactly what we're after - a spoiler tag that hides the text in a black block, but can be seen easily when highlighted.
I think the ADOM parts of the forum need to have this kinda ASAP, since it's farly easy to stumble upon spoilers.
(and there are amny threads mixing spoily and non-spoily.)
While we are on the issue, I would like to ask you all to add a [spoiler] tag to your threads, denoting that you want either your question asked using spoilers, or will freely disclose spoily information therein.
Asking for a separate forum for spoily and non-spoily talk may be an overkill at this point, but it's also an option.