You need to kill the boss, a big spider-looking enemy.You find it on a cave, when you get ddeep enough in it.
Btw now I have beated game with all the classes and all factions.I have to say that my favourite class is wizard, since it has ranged attacks, good damage and nice skills My favourite factions are Phoenix and Mercenaries.Phoenix since Guardians are too peacelowers for me, and Mercenaries because they have best ally variety and they have funny missions.
It was a nice game and I tried it on epic with a ranger but annoyingly when I was on the warder quest where you take the archer called francis to kill some hydromancers and they don't respawn but I died at the same time as I killed one and it didn't count it so now it says I've only killed 5/6 and when I restarted the quest it said 0/6 and there were no more.
yes its really a nice game, many stuff like weapon, armor, etc. I was ranger with guardian and mercen as my ally. Its very easy, I kill 5 black council in final mission without problem.
@Tormentax The Riddle Masters are usually along the fences on the map, or along a river. I noticed that myself. Just search along them and you should find the last one.
key to winning the game: become a rogue, stay on the first rune, add 2 thirds of points to strength and the rest to stamina. choose pheonix,mercenary,and the blade masters. do all the quests