Just have Ramza and Delita with full knightish equipment (so max health and physical damage), a black mage with at least one level 2 spell (I can't remember if they were all the same or if fire was better for that fight), and two others that are running over towards algus (possibly one as an archer, that's what I had. An archer and a samurai.).

I just completely sacked myself. Ran straight at algus and attacked him. My black mage I did a suicide run to cast one last spell on him, then the knights swarmed her. My archer finished him off.

I guess you could do it more methodically (that's what I did my previous game, killed at least the black mages), but that takes forever!

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Be sure you know where you're going with your classes. My first game I had no clue what a Lancer, Samurai, and Ninja were, and I got stuck at the end of chapter three in Riovanes castle (course, that's also due to me saving over my only save game before I went into the castle). This time I went straight for Samurai, Ninja, and Calculators.