Since our last report we have seen Bolvi and his forces fight in a small battle, and we have more to say about them that we couldn't determine by observing their practice.
Given the remarkable innovation of Assault Towers in field combat, it shouldn't be surprising to learn that Bolvi has dedicated much of his use of his Summoning Stone to make the Towers even better in battle. In particular, he sometimes summons a tower faster -- that is with less magic expenditure -- than he should be able to.
And, at times he summons them next to other towers rather than to Walls or even to Architects.
Finally, he uses his Stone to temporarily enhance the strength of the towers, so they withstand damage much more readily. It can be quite frustrating to their opponents.
On another note, there is a new type of troops that Bolvi is fielding. I credit Aaron for noticing this and pointing it out to me. Certain of their common soldiers fight with greater skill and determination against stronger units than they do against weaker ones. Aaron sees that as part of the pattern of Guild Dwarf toughness, as we have already seen in Defenders, Guardsmen and Spearmen. While I agree, I also wonder if there is a measure of pride involved: perhaps they don't exert themselves as hard against "less worthy" opponents.
We believe this is all there is to say about the new developments in Bolvi's army. We will of course tell more if we learn it, but we will probably just continue to report on his movements and interactions with other groups.