Phase Drop

Phase drop is a medical condition that occurs to persons staying in the Free City who have not sworn on the Oathneedle, or who have sworn, and then broken their oaths. 
It begins to manifest in visitors after spending about one week in the Free City with the milder symptoms. Full phase disassociation and probable death usually occurs within one month  of that if not treated properly.
In Oathbreakers, the disease begins to manifest much more quickly, within two or three days of the oath breaking event. Full disassociation generally occurs in two weeks or less

Transmission & Vectors

Phase drop is not considered to be infectious, and cannot be spread between individuals.

Causes

The Free city, as a Demi-plane, has a unique metaphysical alignment within the spheres of existence. This alignment tends to interact badly with inhabitants of full planes. If a being spends too long in the Free city without having aligned themselves to the plane by swearing on the Oath needle, or if they have broken an oath and had that alignment revoked, they being to drop out of alignment with the physical reality of the plane.

Symptoms

Mild

Sweats

Fever

A mild, whole-body vibration

Moderate

A more severe vibration

An intermittent inability to interact with physical objects that are aligned with the the Free city

Mild transparency and/or intermittent invisibility

Bouts of random teleportation

Severe

Almost complete translucency 

Longer bouts of invisibility 

The inability to make sounds or telepathic projections that would allow one to communicate with the outside world

Almost Complete inability to interact with physical objects

Loss of ability to be affected by the force of gravity (intermittent)

Treatment

There are only two known cures for Phase drop
1) Swear on the Oath needle and bring your metaphysical alignment in line with that of the Free City
2) Return to your home plane

Prognosis

You can still cure phase drop if it has progressed to the more severe stages of the disease, however it becomes more and more difficult to treat as the patient becomes unable to interact with the physical world. 
No one has ever recovered after passing into complete invisibility; It is unknown at this stage if they even still exist.

Prevention

Swearing on the Oathneedle, or only spending short periods of time (Less than one week) inside the Free City

Cultural Reception

It is considered bad luck to interact with someone severely affected with Phase drop, and they are generally distrusted, as they are recognized to be either oath breakers or outsiders.
It is considered almost merciful to slay on sight an Oathbreaker who is afflicted by Phase drop, as they are unlikely to find a plane that matches their current metaphysical alignment.

Type

Magical

Cycle

Short-term

Rarity

Uncommon