Yes, the thestrals were indispensable. The new weather team had cleared the sky of the constant, swirling clouds, and while they would reform eventually Forgath was presently enjoying a sunny day - a guilty pleasure for a dark lord if ever there was one. A select few had joined the lower ranks of the magi; while they did not have the same instinctual talent for crystal foci, their innate magics gave them insight into workings dealing with water, air, and shadow. Several of their civilians brought with them knowledge of crafts that were not present among the citizens of Ironforge, including the aforementioned furrier. Granted, not all of them were immediately useful (and Forgath wasn't sure what he was going to do with the beekeeper in this climate) but that was a matter for later. Even more valuable, a small segment of them had military training and experience that was invaluable, including Shadow Mane first and foremost. His crystal pony guards had trained, yes, but largely from scratch; Forgath did not know how to train a quadruped to fight as anything but a mount.