Set item layout:

Plaguebringer's Blade

weapon (any sword), rare (requires attunement)

A wicked-looking sword with a sickly green aura that pulses with malevolent energy. When striking a creature with this sword, it has a chance to infect the target with a magical disease.

Magic Weapon

You have a +1 bonus to attack and damage rolls with this magic weapon.

Affliction

When you hit a living creature with this sword they must make a Constitution saving throw (save DC 15). On a success they are immune to the swords diseases for 24 hours. On a fail the target is afflicted by a disease from the table below. Roll and consult the table below. A creature can only be afflicted by one disease at a time. The disease lasts until cured.

d8	Disease	Effect
1	Frost Fever	The target's speed is halved and they have disadvantage on Dexterity saving throws
2	Blighted Rot	The target's hit point maximum is reduced by every hour.
3	Bloodbane Pox	The target's blood turns toxic. It takes poison damage at the start of each of its turns. Additionally, they have disadvantage on Constitution saving throws.
4	Filth Fever	The target's body is wracked with fever and chills, causing them to have disadvantage on attack rolls and ability checks
5	Blacklung	The target struggles to breathe. It takes necrotic damage if it moves more than 15 feet on it's turn. Additionally, at the end of each hour it must make a DC 10 Constitution saving throw. On a failure, it gains one level of exhaustion.
6	Mindrot	The target's mind is clouded by a creeping fog, causing confusion and disorientation. They have disadvantage on Intelligence, Wisdom and Charisma ability checks, and must roll a d8 at the start of each of their turns; on a roll of 1, they do nothing that turn as they are lost in the haze.
7	Quaking Sickness	At the start of the target's turn, they must roll a d8. On a roll of 1, they suffer from a seizure, rendering them paralyzed until the start of their next turn. A creature who suffers 3 consecutive seizures, dies.
8	Creeping Death	Upon infection, the target immediately takes necrotic damage as the disease begins its insidious spread. At the start of every hour following infection, the victim takes escalating necrotic damage. The damage starts at necrotic damage for the first hour, increasing by each subsequent hour ( for the second hour, for the third hour, and so on).

Plague

These diseases are contagious. Any living creature that touches a diseased creature or takes a long rest within 15 feet of a diseased creature must make a DC 12 Constitution saving throw. On a failed save, the creature contracts the same disease.