“On my mark,” Rowan said, smelling and hearing things that ­were lost even to her heightened senses. “Steady . . .” She sank onto her haunches as Rowan did the same.

   “Come out, come out,” one of them hissed—­so close it could have been inside the tree with them. There was a sudden rustling in thebrush to the west, almost as if two people ­were running. In­stantly, the reek of the skinwalkers lessened as they raced after the cracking branches and leaves that Rowan’s wind led in the other direction.

   “Now,” Rowan hissed, and burst out of the tree.

   Celaena ran—­or tried to. Even with her sharpened vision, the brush and stones and trees proved a hindrance. Rowan raced toward the rising roar of the river, swollen from the spring rains, his pace slower than she’d expected, but . . . but he was slowing for her. Because this Fae body was different, and she was adjusting wrong, and—

   She slipped, but a hand was at her elbow, keeping her upright. “Faster,” was all he said, and as soon as she’d found her footing, he was off again, shooting through the trees like a mountain cat.

   It took all of a minute before the force of that smell gnawed on her heels and the snapping of the brush closed in. But she ­wouldn’t take her eyes off Rowan, and the brightening ahead—­the end of the tree line. Not much farther until they could jump, and—

   A fourth skinwalker leapt out of where it had somehow been lurking undetected in the brush. It lunged for Rowan in a flash of leathery, long limbs marred with countless scars. No, not scars—stitches. The stitches holding its various hides together.

   She shouted as the skinwalker pounced, but Rowan didn’t falter a step as he ducked and twirled with inhuman speed, slashing down with his sword and viciously slicing with the hatchet.

   The skinwalker’s arm severed at the same moment its head toppled off its neck.

   She might have marveled at the way he moved, the way he killed, but Rowan didn’t stop sprinting, so Celaena raced after him, glancing once at the body the Fae warrior had left in pieces.

   Sagging bits of leather on the wet leaves, like discarded clothes. But still twitching and rustling—­as if waiting for someone to stitch it back together.

   She ran faster, Rowan still bounding ahead.

   The skinwalkers closed in from behind, shrieking with rage. Then they fell silent, until—

   “You think the river can save you?” one of them panted, letting out a laugh that raked along her bones. “You think if we get wet, we’ll lose our form? I have worn the skins of fishes when mortals ­were scarce, female.”

   She had an image then, of the chaos waiting in that river—­a flipping and near-­drowning and dizziness—­and something pulling her down, down, down to the still bottom.

   “Rowan,” she breathed, but he was already gone, his massive body hurtling straight off the cliff edge in a mighty leap.

   There was no stopping the pursuit behind her. The skinwalkers ­were going to jump with them. And there would be nothing they could do to kill them, no mortal weapon they could use.

   A well ripped open inside of her, vast and unyielding and horrible. Rowan had claimed no mortal weapon could kill them. But what of immortal ones?

   Celaena broke through the line of trees, sprinting for the ledge that jutted out, bare granite beneath her as she threw her strength into her legs, her lungs, her arms, and jumped.

   As she plummeted, she twisted to face the cliff, to face them. They ­were no more than three lean bodies leaping into the rainy night, shrieking with primal, triumphant, anticipated plea­sure.

   “Shift!” was the only warning she gave Rowan. There was a flash of light to tell her he’d obeyed.

   Then she ripped everything from that well inside her, ripped it out with both hands and her entire raging, hopeless heart.

   As she fell, hair whipping her face, Celaena thrust her hands toward the skinwalkers.

   “Surprise,” she hissed. The world erupted in blue wildfire.

   •

   Celaena shuddered on the riverbank, from cold and exhaustion and terror. Terror at the skinwalkers—­and terror at what she had done.

   His clothes dry thanks to shifting, Rowan stood a few feet away, monitoring the smoldering cliffs upriver. She’d incinerated the skinwalkers. They hadn’t even had time to scream.

   She hunched over her knees, arms wrapped around herself. The forest was burning on either side of the river—­a radius that she didn’t have the nerve to mea­sure. It was a weapon, her power. A different sort of weapon than blades or arrows or her hands. A curse.

   It took several attempts, but at last she spoke. “Can you put it out?”

   “You could, if you tried.” When she didn’t respond, he said, “I’m almost done.” In a moment the flames nearest the cliffs went out. How long had he been working to suffocate them? “We don’t need something ­else attracted to your fires.”

   She might have bothered to respond to the jab, but she was too tired and cold. The rain filled the world, and for a while, silence reigned.

   “Why is my shifting so vital?” she asked at last.

   “Because it terrifies you,” he said. “Mastering it is the first step toward learning to control your power. Without that control, with a blast like that, you could easily have burnt yourself out.”

   “What do you mean?”

   Another stormy look. “When you access your power, what does it feel like?”

   She considered. “A well,” she said. “The magic feels like a well.”

   “Have you felt the bottom of it?”

   “Is there a bottom?” She prayed there was.

   “All magic has a bottom—­a breaking point. For those with weaker gifts, it’s easily depleted and easily refilled. They can access most of their power at once. But for those with stronger gifts, it can take hours to hit the bottom, to summon their powers at full strength.”

   “How long does it take you?”

   “A full day.” She jolted. “Before battle, we take the time, so that when we walk onto the killing field, we can be at our strongest. You can do other things at the same time, but some part of you is down in there, pulling up more and more, until you reach the bottom.”

   “And when you pull it all out, it just—­releases in some giant wave?”

   “If I want it to. I can release it in smaller bursts, and go on for a while. But it can be hard to hold it back. People sometimes ­can’t tell friend from foe when they’re handling that much magic.”

   When she’d drawn her power on the other side of the portal months ago, she’d felt that lack of control—­known she was almost as likely to hurt Chaol as she was to hurt the demon he was facing. “How long does it take you to recover?”