Ezrin is careful about when he delivers his lectures to Ethelred, he checks around the tent, and does not lecture when traveling alongside any others. Nevertheless, After several lectures on each individual Collegia Arcana, Ezrin moves on to an overview of the Weave of Warrens

Magic everywhere and in everything exists in a semi-formalized state, some call this The Weave.. The power is refined, aspected, organized into something like themes, and these themes are what we refer to as Warrens. Some think of Warrens and magical tunnels in reality, others as strands of power that make up reality, some as other dimensions of existence outside of what most humans are normally capable of experiencing, and some old writing refer to them as Planes of Existence.

Many Warrens are accessible to mortals and gods alike; others are – Alien.  Some are virtually extinct, or inaccessible due to ignorance or deliberate rituals of sealing.  Some, in addition, are claimed and ruled over by elements either native to those warrens, or so fundamentally related to them as to make the distinction meaningless.

There is some disagreement as to whether certain Warrens are shared by various Powers, or if those Powers have their own, individual Warrens. For example, most believe the Pont-loi, Pannoi, and Poloi all share the same Warren. Many believe that that Traan-Vilu and Elgin share the same Warren. Most who espouse these types of beliefs hedge their propositions by including the caveat that the Powers occupy different parts of aspects of the Warren. This is most evident in the theories of The Omni-Warren, and Warren-Weave Duology.

I am about to list some Warrens. It is important to take care in speaking, writing or gesturing the names of Warrens. Especially with writing them and gestures. With writing about them, use plain letters, and simple abbreviations, lest you accidentally invoke the power of a Warren. Do not practice the gestures outside of practicing specific incantations that already include the gestures.

Some the Warrens Named by the Sages include:

Warrens particular to each God, or at least each Major God

Elemental Warrens, Air, Fire, Earth, Water. 

And more, such as:

Infernal, Abyssal, Cthonic, Oceanic, Swamp, Elements, Celestial, Astral, Etheric, Elven, Dwarven, Demonic, Gnomish, Cold, Lighting, Stone, Wood/Trees, Light, Darkness, Healing, Shadow, Death, Undeath/Hunger, Draconic, Order, Chaos.

Here are some proposed groupings or Meta-Warrens:

[Here Ezrin draws various web-like relationships between different groups of Warrens in the sand, using simple non-arcane one to three letter abbreviations for the various Warrens as he lists them]

Death – Undeath/Hunger – Chaos – Abyssal – Cthonic

Water – Cthonic – Oceanic – Swamp

Healing – Light – Dian-Cecht -Celestial – Sun

Wood – Plants – Oo-Rin – TyLin

Demonic – Infernal – Abyssal – Chaos

Dwarven – Gnomish – Goblin – Orc

Celestial – Anahsar – Ishtar – Raiden – Torr-Van -Oo-Rin – Ponnoi/Poloi

Earth – Stone – Traan’Vilu – Algin

Fire-Water-Earth-Air

Fire-Steam-Water-Mud-Earth-Lightning-Air

There are more, some get lost in proposing all the possible relationships. Literally lost according to some stories, pulled into a maze of Warrens and lost…

You can see why it is important to use tried and tested materials, sigils, gestures and vocalizations when calling upon magical energies. The potential to connect with unintended energies is very high, and the consequences of doing so can be truly catastrophic.