Look in my chest, find a pack of 3 travesty keys I bought at Zento for 70k. (Sometimes just too lazy to far them)
I rush down, use my keys and...
Someone is there already fighting it...
Although we remain all cool about it, I just hide and let the persons that were there first
finish there job, then just recalled out and got to a nice little agreement..

The same also happened to me at Blighted grove and Sanctuary, even Bedlam...
OK, reason of post.
Would it be hard to put a script or code or whatever to tell us something in the veins of :
" Someone is already in there, do you wish really to go in ? "
Would maybe be possible even to make some "checkpoints" (Entrance to the branch Lady Mel is on, hole leeding to Netopir, altar leading to travesty and such..), popping out that question...
The new rules of Doom didnt bother me at all, cause true you go there for artifacts, but if say, 5 people get to Lady Mel, can be a bit of discussion who gets bark, who gets parrot etc....
Anyone agrees there should be SOME KIND of indication that someone is fighting "x" boss ??