Dithmenos piety

[said46]

Hello,guys. My current character is following Dithmenos and I cannot understand why 6* level of piety constantly drops to 5* without any obvious reason. I do use Shadow Step from time to time, but if it is so heavy in terms of piety that it drops the piety to 5* every single time I use it?

[CanOfWorms]

it costs slightly less than finesse (4-6 per use)