My Wanda is now at level 31 in the beginning of gold difficulty and she kills everything easily what comes in her way. It is a really strong build, very big thanx for the idea, ka243 ! =)
Like I said, I've never really played a BFG-seraphim before, but now I know she will be a very good (and safe and fast) bosskiller!
For maximum damage I let go warden energy lore (or enhanced perception, what I first wanted to take) and will also pick later (with level 65) combat discipline^^