Lord's core concept

Each Lord has their aspect, a thing described by their name, and all the words related to that thing. Each one of them has complete control over those things. Their words can shape, create, manifest, or destroy things related to their aspect. Their Towers and their Domains, the territories that belong to them become closer to those concepts, both in appearance and in properties. For example, a Lord related to water could have a tower that is transparent and moving like water, one made out of it, or one from which water spills through countless pipes or fountains. Their territory could resemble wetlands, a beach, a swamp, or be completely submerged.
When a Lord gets killed, their core concept gets left behind. After all, for it to stop existing, one would have to destroy it completely from existence all over the world not just kill its present ruler. So it stays somewhere in the Lord's tower ruins, still affecting the area around and out of control. Without its Lord, the Domain becomes a very dangerous and chaotic place.

Appearance

For humans without any devices that would let them see aspects, Lord's concept core is completely invisible. They can see how it affects the area and even feel what aspect the area is affected by, but they cannot perceive the aspect itself.
For Faceless Ones and humans with those devices, the core concept looks like a ball of light surrounded by constantly appearing and disappearing, moving, shifting, and vibrating words related to said aspect. As more spiritual beings, Faceless Ones can touch and pick up said ball of light as if it was material. When touched, it feels and smells like its aspect would (if said aspect even has any smell, texture, or temperature.

Interaction and uses

Depending on who wants to use the Lord's core concept, it can either do nothing or it gains quite unique properties.

Humans and Created

For humans and The Created, aspects of Lords are useless. Some Created whose powers are close to an aspect might feel some affinity to it and even become stronger than they would if they interacted with the normal version of said aspect.

Lords

Unless the core concept of the fallen Lord is similar to their own, Lords will completely ignore aspects of other Lords. If they are in some way related, Lords will sometimes pick them up and add them to their own aspect which might slightly increase the number of things they can control.

Spirits

Spirits are pure beings of concepts that can feed on other concepts. The only price for eating a concept that is different from their own might forever change them. As such, presenting them with a pure aspect of something is like presenting a starving man with an endless buffet. Even if Lord's aspect is very different from their own, not many will pass such a feast. A spirit doesn't need a lot of time to start growing and becoming more dangerous when feeding on a core concept. They'll also become way more hostile, protecting their treasure like dragons. But unless someone stops them during the consumption, they will just continue to eat more. At some point, they'll become so large that things on a human scale won't bother them anymore. Those giant deities of aspects might affect the area for some time, but they'll usually wander off, no longer needing to feed on anything to survive.

Faceless Ones

Faceless Ones have been collecting Lord's core concepts even before the Extinction. Whenever one of them kills a Lord, they can interact with their aspect and give it a material form. As a result, Faceless Ones were able of creating weapons and tools based on the concept of a fallen Lord, which they used to kill more of their kind and their Beasts. Once one item is "forged" out of a core, what is left of it can be brought and used to produce more of its copies. Said copies will always be way weaker than the first "Artifact", but having a weaker version of one of those items is always better than having none at all when facing something as powerful as Lord.