Evil Magic over Galvany

When the Hole opened over the fields, there was confusion. The dark aperture occluded the sun as it enlarged from an occult pinpoint in the sky to a wide tear. Baffled by its appearance, the crop mages huddled together. And then the Teertsi gangs began to emerge.
"What... what is that?" Alex's father, an elder among the crop mages, had cried out.
"It looks like the sky is being torn!"
"This is evil, evil magic."
Alex could only agree.
The first sight the Delta folk had had of the Teertsi were the heliothopters, spidery airborne vehicles with only a single rider, pumping pedals and bellows to keep his flimsy craft aloft - but these were only scouts, soon followed by handfuls of airships, proud and terrifying zeppelins. Within short moments, the airships were dropping balloons filled with only enough hot air to slow their descent, and attached to these balloons were baskets brimming with Teertsi ground troops in their oily black armor, made from the hide of no beast Alex had ever seen. From these baskets also emerged the Starcatchers and the Lutanists, who began setting up their equipment on a nearby hilltop. The ground troops charged down the hillside and across the fields of Galvany.