[Zarr]

IMO these characters would be a must for any evil party:
Korgan
Edwin
Vicionia
Jan Jansen

Then one of three:
Yoshimo
haer'dalis
Anmonen
Spoiler
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Though if Anomen passes his test he becomes lawful good so if you want him in a evil party he'd have to fail it. Jaheria and Cernd won't do because if you poison the druid grove(the evil path) I heard they leave.

There is such a thing as an evil knight it's called an anti-palidan but you can't be that class in SOA. However you can be it in the unoffical mod the darkest day which BTW is now apparently compatible with TOB.

I'd say a assassin is more evil than a fighter the whole idea of an assassin is very evil.