Elementals
Elementals are not creatures that command fire, water, air or earth. They are those processes happening without a person inside them: partial form, no personal Time, no Memory, no Will, and a Function that can outlast any witness.
When an Event Has Form
The Codex classifies elementals among the transcendent because calling them alive would already be the wrong question. Their formal profile contains only a partial Body and a functioning purpose. Personal Time is absent, Memory is absent, Will is absent and Soul is absent. They do not live through a sequence of experiences. They happen. A flame that must guard a threshold, a pressure of wind that refuses passage or a body of water behaving as a boundary can possess enough form to be fought without ever becoming a person.
Their origin is associated with the Riot of Elements, the backlash that followed attempts to hold the world in perfect Harmony. This connects elementals to the oldest elven problem. The elves once manipulated rivers, forests, mountains and weather through a direct elemental network. Later magic explicitly treats that kind of pure elemental command as dangerous and archaic: the network became self-sufficient and rejected its users. Modern cultures therefore approach elements through social and metaphysical filters - storm through maritime cult, fire through sacrifice, bone through Memory, nature through druidic relation - rather than pretending raw matter is a neutral school.
At the deepest level of dungeon cosmology, elementals stand at the Threshold of the Beyond before the more individualized Gatekeepers of the Edge. Here their Function becomes architectural. They do not patrol a border because someone appointed them. The border appears as them. Fire, air, water and earth become tests of whether a descending being can continue toward the realm where ordinary distinctions begin to fail. This is why the source calls elementals 'gatekeepers of transitions' even while it distinguishes them from the later Gatekeepers as a separate category.
To a human hunter, an elemental looks hostile because it blocks a route. To the Great Cycle, hostility is an accidental description. A process cannot hate the traveler any more than a cliff hates the falling body. The danger lies precisely in that absence of negotiation: there is no biography to appeal to, no memory to shame and no Will to persuade. One must understand the Function, satisfy it, divert it or survive it.