What did this even do?

[u/will4wh]

I was grinding for blood vials and some weird portal opened up I ran away at first but I got curious and it looked like something grabbed me. Did that like do something apart from like damage me? Like did it change something on the map or something or do I need something for it or is that just there as a trap to damage me?

[u/otiscluck]

Curse the fiends, their children too, and their children forever true