You summon the essence of pure disease and inflict it on up to five incapacitated creatures that you can see within range. Each target must make a Constitution saving throw. On a failed saving throw, the target is infected by the disease. On a successful saving throw, the target can't be infected by the disease for 24 hours.

An infected creature repeats the saving throw every 24 hours, taking 8d6 necrotic damage and gaining 1d4 levels of exhaustion on a failed save. The creature's hit point maximum is reduced by an amount equal to the necrotic damage taken until it is cured. If it successfully saves three times in a row, it is cured of the infection. Any effect that removes a disease grants an infected creature one successful saving throw. Only spells of 6th-level or higher can cure the infection immediately.

Any creature that spends more than 10 total minutes within 15 feet of an infected creature since it finished its last long rest must make a Constitution saving throw if it isn't already infected. On a failed save, the creature is infected by the disease, and on a success, it can't be infected by the disease for 24 hours. The time spent with an infected creature doesn't have to be all at once and doesn't have to be from a single infected creature.

At the DM’s option, you may choose an alternative disease effect, such as one of the diseases described in Chapter Three of The Impermissicon, but the alternative effect should be no more powerful than the effect described above (an effect equivalent to a tier three disease). The DM has final say on such a disease’s effect.

The DM determines how effectively the disease spreads over time. Alternatively, the DM can choose to use the following table to determine its spread. Every 24 hours after casting, the DM rolls a d100 and adds your spellcasting modifier and your proficiency bonus to the result, then checks the table based on that result.

Location. The spread of the disease is determined by whatever description best matches the location where the most infected creatures are. "Remote" means a place where almost no one lives. "Rural" means a place where a community lives, but the community is dispersed, with the largest concentrations being small villages. "Town" means a place where more than a thousand people live in relatively close proximity. "City" means a place where more than ten thousand people live in close proximity.

Intense Spread. The number of infected creatures is increased by up to 50% (minimum of one creature).

Moderate Spread. The number of infected creatures is increased by up to 20% (minimum of one creature).

Mild Spread. The number of infected creatures is increased by up to 5% (minimum of one creature).

No Spread. There are no additional creatures infected that day. The number of infected creatures might decrease, if the DM decides so.