My MC is charisma based (Courtesan/Hypnotist as the main classes), then have Kia focused fully on buffs and heals and int (Acolyte/Scholar as main classes, man I love that Cheer for boss fights), then have Rogue/Fighter Terry focusing on dex, and then bruiser Layla focusing on strength, though after getting to lvl 8 bruiser I started taking rogue levels to her also, mostly for the speed boost ability as low initiative is her main weakness. But Terry was two shotting mobs of his own level too before I outleveled stuff, I first had him using Kravitz's sword, before getting the Gol Claw which he is using now. Terry is okay against bosses too, it just feels weird to have half of a jobs abilities being unusable. In boss fights with him I just keep the speed boost up and alternate between dirty blow and bash rest of the time, as both have 1 round cd.
I do like bruiser a lot too, even though you run out of mana really fast with all those 50+ mana costing skills.
EDIT: I did beat Lagon at lvl 17, or well my party was lvl 17 when I started the fight, went up to 21 I think from the xp gained from completing both phases.