I entered the Tower of Frozen Shadow expecting an immediate fight. I was instead greeted by a coldain strike force who had invaded earlier in an attempt to defeat Tserrina. They hit a road block, however, when attempting to clear out the first floor. Aware of their imminent failure, they asked me to pick up their slack and defeat each floor's master. Once I've done that, I should be able to access the eighth and final floor, where Tserrina is waiting. I must kill her!