|For the final fight at Highbridge, the key is the focus on the mages. From where you start, you will pass by two pairs of Alacran, with one conjurer (Kindess) and a melee. Dispatch both sets and do the same to the archers on the stairs. At the top, take out the black mages (Humility), then proceed to the conjurer healing the main forces (Gotwin Halehex). [Note: if you ignore the pugilists and archers and just kill the mages, like this guide originally suggested, you run the risk of taking too much damage to finish the fight at lower levels.]
With Gotwin down, the Alacran will have no healing and the NPCs can easily mop up the mooks. However, a short while later Gigirya the Guarded will join the fight, coming from the northern stairs. He's a thaumaturge, but most importantly he can summon a Void Slave, which you will have to tank and defeat... if he actually summons it. Shield bash can interrupt his "Void Call" spell, preventing the Void Slave from joining the fight.
Once all the mages are down, it's a simple matter of cleaning up the rest. The Temperance that Mylla is fighting is the most difficult foe with the most HP, so take out all the other enemies first so your NPC allies will focus on the boss.