And which spell can activate this totem...? Which skills i need?
As far as I know the only spell working here is laser ray (Strahl der Macht).
Edit: Sorry, that was completely nonsense. Just mixed it. Not laser ray is needed, it's "Rainig Blood"(Blutregen).
Maybe a different way to activate the tree is to position a party member near the tree and make it bleed. But not sure if this would work either.
Sorry for the confusion with laser ray.
milo