Bojzan Southern Front is currently impossible to complete for new/late players.

[Vahlnir]

So, i am currently slowly pushing towards rank 15. From my experience it goes as follows. People are farming fates/CE/clusters whatever. Castrum pops. 10 people sign up. Other people continue farming w/e they were farming before.
There's no incentive to run Castrum outside of story. Yes it gives you coins and you can get deep essences from saving alll the prisoners, but it does not give any mettle whatsoever, which, imo, is one of the reasons it's unpopular.

Mettle loss in Castrum is inconsequential. You can leave it after dying maybe 4-5 times, and 15 minutes later at MOST you are back to breaking even and probably beyond. No, this is not part of the problem. Or at least it shouldn't be.

[Flay_wind]

Mettle loss in Castrum is inconsequential. You can leave it after dying maybe 4-5 times, and 15 minutes later at MOST you are back to breaking even and probably beyond. No, this is not part of the problem. Or at least it shouldn't be.

One of the reasons, not the main reason.
But it should probably give you mettle for completion regadless.