[Fern]

Overgrown Staff is useless in the majority of cases when it comes to weapon efficiency, which is a pretty bad thing because it's a ten star boss item and rare things should be worth the hassle. I'm not sure about it being Spelledge, neutral towards that notion frankly. Here are some more scaling ideas though:

A) 80% SAN 30% WIL
B) 80% SAN 30% LUC
C) 60% WIL 60% SAN
D) 60% LUC 60% SAN
E) 80% WIL 20% SAN 20% LUC

You could also give it a potential skill. Ideas:
 
A) You unlock Vine Pull for its potential skill (the 1M pull you get from Shapeshifter shenanigans)
B) An invocation that makes flowers spawn all across the battlefield on random spots similarly to Aposemagika. Ideally another effect would accompany this, likely related to Nature spells (ignoring Resistance on Nature spells maybe?)

I'm just kind of spitballing and I don't really know the theming for invocation names so I can't really help in that regard, but maybe there's something for consideration.