As you enter the tombs from the Endless Desert, go down the ladders and go East, if you go north from there there is a random Dark spot (place you can't see without glowing or above light) It is a new as far as I know, I've never seen it before.
Desert
{}{}{}{}
_____{}ladder
_____{}ladder_____[]Tomb spot ( normal)
_____{}ladder_____[] Random Dark spot
tomb_{}--------------[]Tomb spot ( normal, first enemies able to spawn)
_________________[]Tomb spot ( normal)
I know my map sucks, best I could do on short notice, if this is a known issue, i'm sorry for posting, I looked and couldn't find any reference to it.