Halsin tells us there is more to the grove than mere druids, that it has a power of its own.
I expect shadowdruids want to seal the grove so as to make the shadowcurse (whatever it is..) not just unbreakable but stronger and probly grant some fun shadowpowers... which may or may not clash with the tadpole...
Ofcourse in the end they too work for whoever is behind the absolute (probly ioulaum). Luckily shadowheart has the box (Jergal inside? Nothing less than a god afterall can hope to stop new and improved Ioulaum lvl 80ish and more op powers than 10 bars can hold. Actions? hundreds per round)
