Huh? I thought I had pretty good scout coverage of the area, but I guess I must have still missed something
Here's what I
did see:
Ermor attacked and captured Kseftia (25) from the sea, thus cutting off Agartha's escape rout.
Ermor attacked the Agarthan force that had him under siege at Pythium (8). This force was expendable (no mage support), but large enough to convince the Agarthan AI that it was OK to burn gems (saw lots of elementals summoned). As Ermor had three forts in provinces bordering Pythium, full of his undead chaff, such a move could have been easily anticipated.
For the storming of the fortress at Pythium itself, I had the Battle Replay Bug. In my version, Agartha won a very Pyrrhic victory, capturing the fortress, but losing most of its army in the process, while Ermor's pretender and mages retreated safely. So, what really happened there, I'm not sure. But in my version, Ermor cast both Wailing Winds and Winds of Death, so that likely happened in the real battle - again, something one might anticipate from Ermor.
So where was the douchebag move?