I like it. +1
Also, I believe this fills the dark druidism role better than blood magic druids. Far better. To be honest I've never even heard of evil druids and I've been around a while. I'm not saying it won't be niche, because it will be to an extent. This lore was primarily made to aid the Oaks section of Xionism, and I think it works wonderously. A nature based dark magic isn't something we really have. We have spirits, lifeforce, blood, ghosts, ocean things, why not nature? I think it'll be a worthy addition.