The backpedaling forces of Ermor are the next target for the giants (or one of them rather), as Mictlan isn't worth the effort, acts as a convenient barrier from Eastward threats, and will be easily subsumed at any given time by the burgeoning Niefel forces. Oceania has done little of note from the sea, leaving the majority of the giants' coastal domains without fear. Unless the forces of C'tis and whomever is in the far North take action, this game is Niefelheim', without doubt.
