Legendary dungeons are kind of unique in RTL and which brings up a couple of questions

When can Monsters activate?

a) Normal Descent rules aka can only activate after the area is revealed

b) Can activate imediately on first overlords turn

Monster Spawn cards

a) Can use spawn card once per area as per normal descent rules then need to flip the eyes to spawn again.

a) Can be played once for the entire legendary dungeon then need to flip the Eyes to spawn again

The question came up since these are the first multi-area dungeons in a RTL campaign and as such the behavior is questioned. 

Emeketos said:

The answer is (a) is both cases.  Areas still work the same way in the AC game as they did in vanilla (except for the added limitation of the spawn marker, of course.)  The regular dungeons only have one area per level, but the rules for those areas are still technically the same.

Also, keep in mind that many of the rumour dungeons have two or three areas on their final level.

The answer is b) in the second case.

RtL, pg. 17: At the start of every dungeon level, the overlord places the reinforcement marker in
front of him faceup (the side with the red eyes). 

Unless he is playing SoB rumor or keep levels, which have the ruling you mentioned.

Parathion said:

Huh.  I could've sworn the rule was to flip it up as each new area is revealed, even in RtL.  I must be getting confused with the suggested ruling for using the spawn marker in vanilla games.  Oh well, I stand corrected.