Light breathed over him.
It was not the thin, pallid light of the city moon; it was warm, viscous, threaded with gold and green, as if sunlight and sap had fused and decided to flow. The space around Caelum thrummed with it. Leaves sang in slow chorus. Flowers opened and closed as if inhaling breath. Roots arched like living stairways and small streams ran in impossible patterns overhead, flashing fish that looked made from glass. The air smelled of loam and rain and the sharp sweetness of crushed sap — everything alive and insistently present.
He had expected a vision. He had expected something small, a trick of his head or the vague echo of a childhood grove.
This was a world.
He stepped forward and the ground answered with ripples of moss that rose to meet his boots. Tiny lights — motes that were neither insect nor ember — braided themselves into threads and wound through the trunks like veins. Ferns bowed politely as he passed; a stag of light glanced between trunks and vanished as if embarrassed to be seen. The place radiated an intensity of life Caelum had felt only once before: when his hands had sunk into warm, newly-risen flesh of a living thing and felt it answer.
He forgot for a second the inn, the city, V's lazy breathing on the other side of the wall. He forgot hunger and fear and the odd, clumsy shame of wearing clean clothes for the first time. Awe — a cold, bright kind of awe — slid over him, and he moved through it like a thief through a cathedral.
A voice, low and dry as old bark, cut through the wonder.
"Welcome, Last Heir, to the Forest's Inner Realm."
The guide's sound seemed born of root and wind together. It had no gender, no age — only certainty. The guide sounds different here.
Caelum turned. "This… this is inside my head?" he asked, the words tasting unreal.
"No — and yes." The guide's tone was patient, amused. "You cannot enter this place with your feet. You enter it through the sigil on your brow, through the thread of blood that links your consciousness to the living world. It is a domain, a private world folded within your soul. Vast, old, and hungry."
He reached out, and a vine curled to coil around his wrist without touching him, like a cat nudging an owner. The sensation was intimate and terrifying; it felt like the land remembering a name.
"Is it… a place to cultivate? To take in forest mana?" Caelum's voice was too small in that magnitude.
The guide chuckled, a sound like leaf-rustle. "It is more than a spring to drink from. Think of it as a workshop and a throne. A domain."
"A domain?" The word tasted heavy and enormous.
"Yes." The guide's voice widened, the air itself seeming to echo the explanation. "A domain is a fragment of this inner space you can summon into the world. You fold part of this place over the battlefield. Within your domain, your will becomes law. Trees answer you like soldiers. The wind listens. Roots become hands. You are absolute inside it."
Caelum pictured it in a flash: a ring of trees tearing open the earth, a forest rising from the ground with his mind, enemies stumbling into an ocean of living limbs. His chest tightened with a savage, cold delight.
"You mean I can—" he began.
"Summon a forest and be a god within it, yes." The guide's tone was careful now. "But gods here are bound by cost. Domains are not toys."
"Cost?" Caelum felt a small flare of irritation. "I have drawn mana from trees before. I can take what I need."
"You can draw their breath, yes," the guide said. "You are favored by nature. You will find the burden reduced. But a domain consumes more than mana. It consumes ordering. Control. Concentration. You must hold the world together in miniature while you command its fury. Every tree you summon is a thought you must maintain. If your mind blinks, your control frays. If your mana runs thin, the forest collapses like paper. Worse — if your opponent also commands a domain stronger than yours, they can tear yours open and your order will bleed out."
Heat snaked along Caelum's spine. "So if someone stronger than me… tears my domain—"
"You will be wounded in ways the flesh can remember." The guide's voice was blunt. "Domains tear at the soul. It's not only about the loss of land; it is being unmade for an instant where your mind is the battlefield and it breaks."
A cold steadiness settled in Caelum. "Still. It's powerful."
"It is." The guide's tone shifted, a fraction softer. "And it changes things. The way your race eats and grows — you will not only extract life; you will organize it. For you, summoning is not calming, it's overwhelming. You do not coax; you devour. That means your domain will likely reflect that — a storm of teeth and roots, not the gentle grove you imagine now."
Caelum felt something like a grin thread through his chest. "So it will be cruel."
"Precisely." The guide's voice hummed with an odd pride. "And be warned: domain-use is not continuous. It is a blade you unsheathe. It draws long and deep. Once you fold a portion of this realm into the world, you will spend much to maintain it. Most who possess domains use them rarely because it is easier to die unremarkably than to be consumed by your own power."