First off, i know this is asking the impossible but if we could please keep the discussion on-topic that would be fantastical I don't mind if you disagree with me and explain why, but please can we be rational hehe
Adjust Biococoon so that advy can only train X perks into it. I'm not sure what that number should be, but i'm guessing between 6 and 8. This would essentially remove BioRegrowth from advy and make their coon a little less effective.
Having a 220 advy (melee for years and just recently went ranged to try it; very active in pvp) and having fought the onslaught of FotM ranged adventurers I think that this could be enough to have a large impact in real pvp without dropping a nerf-hammer on the profession.
Note, this idea is not my own. It was discussed and formulated with my favorite Nanomage Enforcer on RK2