Chaos
Chaos is an integral force in Nodd, one which has long been thought to counterbalance excessive order by causing bizarre, horrific incidents. Chaotic catastrophes strike anything too orderly, whether as small as a single citizen or as grand as the City itself. Chaos follows no particular rules by it's very nature, a fact which hangs over the head of every citizen - The Council encourages all citizens to indulge and fuel the chaos in their lives.
In bygone times chaos was less well understood - only a rare mage who could alter these catastrophes, either by diverting them or directing them to affect something else. The Council in these times performed many experiments to attempt to glean the nature of chaos and whether it can be controlled - one of the most notable of which led to the Night of the Mothertoad and the rise of the first citygods.
Corruption
Corruption is typically a gradual process, where the afflicted individual becomes more in tune with the City's chaotic nature, becoming more monstrous in the process. The exact cause is not very well understood and proves difficult to study, but most citizens believe corruption is primarily caused by frequent gloam exposure. Mages often suffer corruption over their careers, though any citizen can experience it - especially as they age. Certain circumstances may induce acute corruption, where an individual undergoes a drastic change in a short amount of time. Acute corruption often ends quite poorly for the victim.
Attunement
Attunement is a form of corruption which primarily affects objects, where an object aligns with a particular aspect of magic. This includes artifacts, which may align with a different aspect than what they were created - for instance, an Omnillian wand that sutures wounds closed attuning with the Life aspect may instead make wounds rapidly scab over. Attunement typically changes the appearance of a given item.
Mundane objects handled by typical citizens change slowly, if at all, and rarely in any appreciable manner. Mages are more likely to induce attunement in an item, even unintentionally. Heavily magical items are more likely to have their attunment changed, and even placing one's focus and intent upon an item for an extended period may be enough for the user's beliefs to alter it. An artifact with an attunement that opposes the user's beliefs is more difficult to use, and resists any change in it's attunement from said user.