Radeka is a fun fight, the hardest in Act 1, I always start it with my party unprepared and ambushed, like the first time (where I lost miserably). It's the only fight where I had a dead party member in Act 1 in the release (on Classic).
In my opinion leave Radeka alone first. She is astonishingly weak after she called all her minions in. The only dangerous contribution from her during the fight is usually shackling one party member which means his death of course (it was always my main she shackled). I first kill the pesky beetles, most dangerous for me because of usually low magical armor in the group, then the raised scholar, then Radeka and the rest of the zombies. You should have items on level 5 to 6 for armor. No source skills are needed in Act 1.
