Chaff Demons

Alex's father and the other crop mages now agreed that it was time for action, and so, strengthening and redoubling the hexes they had made on the chaff demons, they sent them at the intruders. But the chaff demons were no match for the Teertsi ground offensive, and again and again the straw men were beaten down, trodden underfoot or exploded into nebulae of hay, only to be brought into being again by the tireless crop mages.
"We can hold them! Keep them together, lads!"
Alex prayed that his father was right. He was almost too young to believe that his father could be wrong.
When the first wave of shock troops met the straw men in combat, they had smashed them with brute force. The crop mages pooled their guile and arcane energy, and the straw men were whirled back into being, forming larger and more powerful homunculi, which seemed momentarily to push back the Teertsi ground force. But then Alex had witnessed a terrifying sight, as some amongst the ground force drew forth lit torches, and set their comrades ablaze. Such was the nature of the Teertsi armor that it protected the wearer from the flames, while feeding the blaze. Alex watched as the burning soldiers tore a swath through the straw men, which kindled almost immediately into towering infernos, exploding from within as the crop dust took.
Trolls, Alex had seen, on one memorable (and quite frightening) occasion when he had traveled with his father to the Mithwood, to trade with the people who lived there. But these invaders, in many ways troll-like, were different. The trolls had been ruthless, but had only been protecting what was theirs. These people were relentless, intent only on breaking through to Azure Spires and neighboring Galvany.
And eventually the crop mages and their allies had had to do just that: to let the Teertsi pass through, and hope that they had given the twin cities of the Delta adequate time to prepare their defenses.
Had this only been the case, the occupation would have ended there, but there had been strife between the cities, and so the cities were prepared for attack, but not from this direction, and the reinforcements they mobilized were delayed.