He had seen this on his first look, but it hadn’t seemed dangerous—Morgon bore down, looking more closely. He had learned many tricks at the university, and one was how to make a lens of air. Morgon adapted it and cast, and instantly found himself the victim of his own workings—the simulacrum of the sticky paste was too coarse-grained a reproduction to examine in the aethereal.

In the real, he emerged, lumbered to a stop from a sprint, and tried not to fall into the fizzing black sludge that had once been Hetty’s second horse. He worked a sample into the air in front of him, cast the lens of air, and then moved it—

The black-purple stuff was alive.

Fifty yards away, Ser Milus was walling the company’s dying horses off from the rest of the army. He had no idea what was killing his horses, but he’d seen enough war to fear infection and the rapid spread of something—some horrible equine plague. Or a curse, or a hermetical working.

The horses at the back of the column were dying, and his own sight told him those at the front were not.

But men were turning and riding back to see.

He ordered men on foot to run forward and order the rest of the army to ride on, and then he thought of Morgon’s box. But by then it was too late, and his beautiful eastern riding horse retched black bile and fell, and Milus was on the ground.

The first horse to fall exploded. And the air filled with fine black spores.

Morgon was less impressed by the spores. Spores he knew how to handle. Morgon raised potentia, made ops, and cast, almost without access to the aethereal or his palace. He could work fire without conscious access to his powers.

The cloud of spores flared and was gone.

Another dead horse exploded, and another.

Mortirmir cast, and cast.

Somewhere between the sixth horse and the ninth, he saw a more elegant solution. He dug the tip of his dagger into the sticky black stuff and used a simple like to like equivocation, and then displaced the stuff with fire.

He had not thought through all the ramifications of his working, and he was shocked to see several horses burn—screaming—or explode into fire without ever seeming to have contracted the plague. He had thought far enough ahead to protect the original sample on the wyvern’s talons.

The rest burned.

An hour later, Ser Milus looked over his rearguard—now fewer than one man in ten was mounted.

They’d lost horses but none of the oxen. They’d lost almost all the company’s remounts and more than half of the war horses.

They were on foot on the rolling, gravelly fields at the foot of the Green Hills.