Hey, new player and user here.
I just had my first experience with tombs.
It didn't turn out well (probably a foregone conclusion).
Came across them when my adventurer and her party were trying to find a bandit leader in a hamlet (the tombs were right next to it). He wasn't in town for some reason (speaking of which...what's the point of ruling a town thats nearly completely abandoned or ruined? The only people in town were his goons), so I figured he might be hiding in one of the tombs. The first 2 (there were like 5 on the outskirts of town) were somewhat uneventful, aside from some traps.
The third one (the biggest one as well) was fairly uneventful as well until I got to the top and saw a mummy. It wasn't really doing much, just sorta following my character but not really attacking. Of course, as I was running out of the tomb a horde of skeletons came to life and slaughtered my party. Looking at Legends Viewer, turns out one skeleton struck down all three of my characters.

Looting the dead was probably a bad idea.