I was under the assumption that all someone needs to do is Murdunk's Last stand to unlock Tier V Journeyman mercs? This true? Or do you have to do all:
Find Your Allies
Whom Frogs Destroy
The Wrath of Korascian
Disrupt the Siege
Champions No More
The entire arc ends with a group mission from Ylatra, Murdunk's Last Stand, where you set an ambush and kill off 35 reinforcements (bring dps!). With the reinforcements cut off, the balance swings back to the denizens of Rathe and the timeline is restored completing the theme.