The thing that slithered into our world was the size of a horse, but lower, longer, and leaner. It was canine in shape, generally—a quadruped, the legs more or less right, and everything else subtly wrong. A row of short, powerful-looking tentacles ran along its flanks. A longer, thicker tentacle lashed like a whip where its tail should have been. The feet were spread out, wide, for grasping, kind of like an eagle’s talons, and where its head should have been was nothing but a thick nest of more of the tendrils. It had something like scales made of mucus, rather than fur, and flesh squelched on flesh.

“Cornerhound,” Ebenezar said, his voice purely disgusted. “Damned things.”

The old man looked weary and obdurate, like a stone that had been resisting the sea since the last ice age. His expression was annoyed.

But then I noticed one of the more terrifying sights I’d seen in my life.

Ebenezar McCoy’s hands were unsteady.

The end of his staff quivered as they trembled.

My mentor, my teacher, the most feared wizard on the planet, was frightened.

He stepped between the hound and me and lifted his left hand as the thing stood there for a second, dripping slime onto the ground beneath it and seething. Dozens of little mouths lined with serrated teeth opened along its flanks, gasping at the thick summer air as though it was something that the creature found only partially breathable.

Then the cornerhound crouched, its body turning toward us with serpentine fluidity. The cluster of tentacles around its head began to quiver and undulate in weird unison, the motion becoming more and more energetic, and a weird moaning sound erupted from the creature, descending swiftly down the scale of audible sound until the tentacles all undulated together in a single quivering movement, and suddenly flew forward at the same instant, with a sound so deep I could feel it more than hear it.

The old man lifted his hand with a single sharp word, and a wall of pure arcane power blazed into light between us, its surface covered in sigils and formulae and runes I had never seen before, a wall of such density and complexity that it made me feel young and clumsy for the first time in years.

Something hit the wall with a visible impact, sending out ripples of energetic transfer through its surface, making it suddenly opaque with spreading concentric circles of light, and the ground quivered so sharply that it buzzed and tickled at the soles of my feet clear through my shoes.

Ebenezar shouted, “Concentrated fire works best!”

And then there was a flash of light and a huge sound and an invisible tsunami grabbed me and threw me off my feet.

As I went down, I saw the old man’s shield wall shatter, as a thousand pounds of Outsider came crashing through it. Broken shards of light streaked in every direction as the cornerhound’s talons ripped the shield apart. The energies released were tremendous, and in their wake, runeshaped patches of fire burned on the cornerhound’s flesh—but the creature shook itself in a twisting shimmy as it landed, shedding the flame like water, and slashed an impossibly fast claw at the old man.

I lay there stunned, but Ebenezar had been to this dance a few times before. The old man didn’t even try to pit his speed against the Outsider’s. He was already on the way out of talon range by the time the thing decided to attack, and it missed him by inches. The nest of tentacles sprouting from the thing’s neck snaked toward the old man, and the cornerhound’s body followed.

The old man lifted his right hand overhead and brought it down with another ringing word, and unseen force came smashing down on the cornerhound from overhead like an invisible pile driver. But as the magical strike slammed home, the cornerhound’s scales undulated in a nauseating wave, tentacles flickering. There was an enormous crushing, grinding sound, and in a circle around the terrible hound, the concrete was crushed to gravel, though the hound only staggered.

Before the Outsider could recover, the old man shoved the end of his staff to within six inches of its head, shouted a word, and unleashed a beam of fire no thicker than a thread and brighter than the noonday freaking sun.

The cornerhound rolled, and instead of cutting the creature in half, my grandfather’s spell sliced off the little tentacles upon the creature’s flank and two-thirds of its tail.

The Outsider’s tentacle cluster swept toward Ebenezar, quivering wildly, and though I couldn’t hear anything, the air shook like the speakers at a major concert, the air around them rippling with something that looked like summer heat waves on asphalt.

The edge of that cone of quivering air emanating from the Outsider’s tentacle face brushed against my grandfather. The old man sucked in a short huff of surprised breath, staggered, and collapsed.

Sudden terror for my grandfather crashed over me, mingling with my frustration and rage from moments before, like gasoline being mixed with petroleum jelly.

And the Winter mantle gleefully threw a lit match.

I thrust the end of my staff at the creature and shouted, “Forzare!”

Once again, the cornerhound crouched defensively, tentacles quivering—but the old man’s fire spell had seared half of them away, and on that side, my spell hammered into the hound like a runaway Volkswagen. There was a thump of impact, and the thousand-pound Outsider staggered several steps to one side, talons raking at the concrete in an effort to resist. The thing was incredibly powerful.

Right. See, the thing about supernatural strength is that to use it effectively, you’ve got to brace yourself against the ground or terrain or whatever—otherwise, all you do when you lob a supernaturally powerful punch or toss a tractor truck is throw yourself a ways back. Get something super-strong off its balance or off the ground, and it isn’t nearly as dangerous as it was a second before.

So while the cornerhound was still sliding across the concrete, I summoned my power, gathered it into a small point, focusing its purpose clearly in my mind, and shouted, “Forzare!” again, and flung the beastie straight up off of the ground. As it rocketed up, I gathered energy frantically again, waiting to line my shot up with the side of the creature Ebenezar had wounded as it tumbled back toward the ground, and then I focused forward and shouted again, unleashing even more energy.

This time, the telekinetic blow struck the thing like some kind of enormous batter swinging for the fences, and it flew down the alley, across the nearest side street, and out of sight. A moment later, in the distance, I heard the sound of something smashing against what sounded like a mostly empty municipal trash bin.

I staggered, suddenly dizzy and weary from throwing the three energy-intensive spells back to back. I stumbled and had to lean on my staff to keep from falling, but I made it to Ebenezar’s side and helped him sit up.

“What happened?” I asked him.

His voice came out rough. “Infrasonic attack. Like a tiger’s roar. Super-low-pitched notes, below what humans can hear, capable of making your organs vibrate. Can have a bunch of effects …” He blinked his eyes several times, owlishly, and then said, “Hell of a thing to try to stop. Help me stand up.”

I did, drunkenly. “How tough are these things?”

“Very,” he said. He planted his staff and blinked several more times, then peered around and nodded. “Very damned hard to kill.”

“Then we don’t have very long,” I said.

“Out of sight and clear of people,” he said.