On my second playthrough, I'm at level 7 in the great trial, and completed the solo quests for Meave and Kane. Now the remainder runs into big group of opponents from the avatar, with 3 portals spawning them.(In the blue part of the map, in the upper left corner) Now unless I'm very mistaken, with my first party I had to do that fight with the 4 left-over characters, which was hard enough, but this time Whisper is put there on her own. And she doesn't stand a chance. Even switching back to easy she can just about take down the first portal, but at the second she gets overrun.

Is this a bug, or am I mistaken about my first run through and is this intended, or perhaps the result of certain choices I mad on this level? If so, how do you win the fight??

Its "non-obvious"... Hopefully you've found a solution by now...

When you're down to one character of your original party, go to town, come back to the tower, and pick the remaining characters to fill out your party (before that fight - obviously..)

I ran into this too..

OK, thanks zzqzzq_zzq. Now I understnad what happens here:
- Whisper was the only member of my regular fighting group that wasn't 'abducted',. The encounter does allow you to change your party, but since I hardly ever use that option, I just clicked 'fight'. [So there is no need to go back to town in this case.]
- In my previous run through I probably did another encounter first where I could alter my fighting group composition, so it was more obvious what needed to be done. (although I'm not quite sure which other encounter you can do at that point)

I do think the programmers could have made this a bit more user-friendly by showing you the change the party composition dialog directly after the 'abduction'.