So some friends and I have started this modpack recently, and it's quite good, having a great time, except suddenly I start taking damage, half a heart at a time, in intervals of exactly a minute. There are no mobs, no radiation, absolutely nothing that could be harming me and even after death it continues. The death message is "Your soul have weakened" which is also entirely unhelpful.

I don't know if it affects other people as it is around midnight at the moment and there is no one else that can test, but I'd like to get some feedback on this regardless, as rejoining doesn't solve the issue for me either.

I've searched everything related and the only (dead) thread I could find mentioned something about Blood Magic, but no one on the server has done anything at all involving that mod. Any feedback at all would be appreciated, it's not gamebreaking at all but it's still pretty annoying.

I am not sure why I went to look into it, but...

I assume you mean this:

Quote

"tombstone.death.beyond_the_grave": "Your soul have weaken"

Its from Corail Tombstone apparently.

@God of VelcroIt's Tombstone and it's explained in the compendium in game (see lost tablets, knowledge of death & familiar receptacles)
When theses items recover, they drain your life.