Another Credo Idea(alchemy was suggested many times before, but not as credo)
Base on Mystic and Gardener
1. Further improvement baseline quality of herbs picked&harvested
2. Traverse swamp faster, ability to eat leeches(100% chance to convert certain wounds into leech burns)
3. Bonus output when craft opium, grist, flour, tobacco and pepper.
4. Chance to double when craft healing stuff
5. Increased chance to get rare parts when butchering(pawbones, claws, fisheyes, dark heart and so) and from foraging/other activities: ant empress, deathhead cryssalis, itsy bitsy spider, weird beetroot. Not affect mining stuff.
Also I though about:
Increased final quality of healing products
Int bonus
Ability to craft special leech blood potion
Maybe u have some additional ideas?