[Kobal2]

Avoid.
It's not the toughest indy defence there is but among the really tough ones it's the most common, and it's annoying to deal with without forces tailored to kill them (even more so in CBM, where the woodsmen blowpipes also paralyze) : decoys to make the bowmen and blowpipes run forward ; some hard-hitting troops (or lots of archers set to fire large monster) to kill the bloodvines quick ; and if possible something with high HP to soak the blood spells harmlessly. If you can afford it, you could also consider sending small groups of disposable troops first so that the druids use up all of their slaves before the real assault.