Question How would you implement...

I'm going to be adding some more races to Luminari. One of my all-time favorites is Drow. I want to implement an innate darkness ability and I imagine I'll be making a spell at the same time.

At first I was just going to do an AoE blind. But that really wouldn't be how darkness works

Another idea was to make the room flagged DARK for a set amount of time.

So if I decided to go down that route, how would you make a spell (or spell-like effect) change the room flag for a set amount of time?

No quick away about it. The two "easiest" options I can see is to continue off the foundation for the event system set in 3.63. It already allows for events for mobiles and descriptors, with rooms/objects coming soon. Then you could just do your ability, and set an event to disable ROOM_DARK after X seconds. The other option would be to duplicate the "affects" system and use it on rooms. If you were going to do a large number of AoE room affects, I'd go with the generic "affects" system route, but if you have more complicated stuff in mind, the event route would be better.

Looks like someone already developed this a ways back.

circlemud.org/pub/CircleMUD/contrib/code/rooms/roomaff.txt

I went ahead and tested it out, works great... very little changes needed to get it working too.