After surrounding the second tower with viol corpses, party set about solving the mystery of how to destroy it. It turns out this particular tower didnt have a magical entry cave. Instead all they really had to do was kill the remaining wizards left at the spire and destroy the crystal of evil floating atop it.
A large number of the wizard were overcome with grief at the atrocities they had committed and still intended to commit and threw themselves from the summit seemingly of their own accord. The remaining few were easy to mop up after they threw a few fireballs hither and tither.
Having taken the tower and destroyed the dark crystal, the party doubled back south to pick up their army of geicos. More dead viol wizards later they continued north to the Viol stronghold. The wizards summoned a storm on us, and we persevered over that shit.