The two events happened in the space of a single heartbeat, two fronts of a silent war erupting at once.
In the secluded corner of the island, Shiro, a blazing streak of golden light, struck the Hollow leader's hand. His fangs, imbued with the pure energy of their bond, sank into the pale flesh. The leader let out a piercing shriek of pain and shock, his concentration shattering. The black obsidian communication stone slipped from his grasp, struck a rock, and cracked with a sickening finality, severing the connection to his dark master. With a snarl of pure hatred, the leader forgot everything else, lashing out with a claw-like hand at the tiny serpent who had dared to assault him.
Simultaneously, in the center of the mire, the Heart of the Sanctuary roared to life through Ren's conduit. A geyser of brilliant, silver-green light erupted from the bottom of Kasai's pool. It was not water, but pure, undiluted life force. The column of light slammed into the underside of the Great Turtle's shell, washing over him in a cleansing torrent.
The effect was instantaneous. The creeping violet veins on Kasai's ancient skin sizzled and retreated as if touched by a white-hot iron. The clouded, weary film over his eyes vanished, and his eyelids snapped open, revealing irises of a deep, intelligent, earthy brown. A colossal, telepathic roar, not of pain but of pure, unadulterated life and fury, exploded across the entire mire. It was the sound of a continent waking from a nightmare. ENOUGH!
The four Hollow still chanting around the Blight-seed were thrown into chaos. Their ritual was broken, their leader was under attack, and their docile captive had just become a font of terrifyingly pure energy.
Kasai moved. The water of his pool, which for weeks had been a black, stagnant soup, began to churn as his own immense, purifying magic reasserted itself. With a surge of power, he created a massive whirlpool around the Hollow's island, the banks of mud and dead roots beginning to crumble and wash away. Two of the robed figures shrieked as the ground beneath them gave way, sending them tumbling into the churning, now hostile water.
Back in the grotto, Ren felt the explosive awakening as if it were his own. The sheer power he was channeling was staggering, a river of life flowing through him that threatened to tear him apart even as it fueled his allies. His vision narrowed, the beautiful grotto blurring at the edges. The scar on his leg was a point of agony, screaming in protest as a torrent of its antithesis flowed through him. He grit his teeth, knowing he had to maintain the flow, had to keep feeding Kasai the strength he needed.
He could feel Shiro's desperate battle through their bond—a whirlwind of dodging, striking, and narrowly avoiding blasts of dark magic from the enraged and now-panicked leader. Shiro was buying time, keeping the leader from reassuming command of his crumbling operation.
The two remaining chanters on the island, seeing their ritual site being washed away by Kasai's whirlpool, finally broke their terrified paralysis. They turned to unleash their own blight magic at the awakened turtle. But it was too late. Kasai was no longer a dormant victim. He was the master of his domain. With a deep groan of ancient power, he brought one of his colossal, pillar-like legs down upon the edge of their island. The entire landmass cracked and splintered, throwing the Hollow and their precious, half-grown Blight Heart into the raging, cleansing vortex of the pool.
The leader, locked in his battle with Shiro, saw it all. He saw his mission in ruins, his prize awakened, his forces in disarray, his connection to his master severed. A wave of pure, nihilistic fury radiated from him. If he could not claim this place for the Unraveling, he would scar it beyond recognition.
Ignoring Shiro for a fatal second, the leader threw both of his hands forward, not at the turtle, but at the pool itself. He unleashed every last vestige of his power in a single, spiteful wave of concentrated blight—a tsunami of black, corrupting energy designed to re-poison the water and cripple the waking Guardian once and for all.
Ren watched through his bond with Shiro, helpless, still pouring all his energy into fueling Kasai's revival. The wave of absolute darkness rushed across the water, about to slam into the newly awakened Guardian of the Mire.