Plague

Plague is a negative status effect that has 4 different stages, starting with debuffing the players healing rate and ending with damage until death - leading to a loss of Max HP. Plague only starts to appear after reaching the The Beneath

Mechanics
The player can contract Plague by the mobs that carry it, no matter the stage of Plague the mob is carrying you will always be given Plague I. In full the plague effects are:
 * Stage I: Regen rate and effectiveness reduced by 50%
 * Stage II: All forms of HP regen are blocked
 * Stage III: Player takes occasional damage over time
 * Stage IV: Player takes damage more often until death. Player Max HP is reduced unless a Healing Stone is used.

Plague Mobs
There are only 4 mobs that naturally spawn with plague, those being: All of these mobs only spawn after The Beneath was reached.
 * Plague Zombie
 * Plague Beast
 * Plague Rat
 * Corrupted Enderman

There is also a Plague themed invasion, known as the Pestilence Wave.

Curing Plague
Plague can be cured with certain items, each with varying chances of success.
 * Bundle of Sweet-Smelling Herbs: 10% chance to cure Plague. Crafted with 8 flowers or vegetables and 1 assorted vegetable which in of itself needs 9 vegetables. You get 9 per craft
 * Old Treacle: 25% chance to cure Plague. Can be crafted with Syrup and a Bottle o' Enchanting or Syrup, a Glass Bottle and Gray or Red mold from the nether.
 * Plague Leech: 50% chance to cure Plague. Drops from select mobs.
 * Plague Stew: Will always cure the Plague. Must be crafted with each of the 3 cures above and a Bowl.
 * Purifying Liquid: Will always cure the Plague. Will be thrown like a Splash Potion. Can be crafted with a Golden Apple, a Diamond, Plague Essence and a Glass Bottle.