neobolts
Explorer
Druids are into recycling. Seems legit.
Seriously though, Druids are supposed to be about balance, so an evil Druid doesn't fit too well for me personally, but he could be an outlier, with a twisted logic that as life and death are part of the cycle of nature, death should be no barrier. Upon death, the personality leaves the body, and the body becomes just a bunch of organic material much as rocks and trees are. So, necromancy and Druidism could work, but evil and Druidism is for me, a bit more difficult to square (but then I'm an old school AD&D head so true neutral Druids = the norm for me).
The concept is a breakaway sect of druidic terrorists that revel in the savagery of nature. The traditional druids are horrified by this unbalanced worldview. The necromancy is another layer on top of that to add more undead for the undead hunter.