Curse

Curses are debuffs, applying negative effects to targets for a duration.
Normally curses must be cast at a point within line of sight of the caster, but those that apply their effects within a radius can apply to targets not in line of sight but within radius, even if there is a wall or closed door in the way. This can be a useful scouting tool, since cursed targets are illuminated.
Using Fade and Cleansing can reduce curse length: Fade must be active at the time cursed, while Cleansing can be active after cursing since it applies to remaining curse length every two seconds. [1]
Drinking from a Well will cure a curse immediately, as will visiting a Healer.

Only one of the following can be active on a unit at one time, as indicated by the overlay displayed above it:

Overlay	Curse	Native Source(s)
	Amplify Damage	Necromancer Oblivion Knight Stygian Fury [[D2 Unique monster#Cursed\|Template:D2 Unique bold]]
	Attract	Necromancer
	Battle Cry	Barbarian
	Blood Mana	Succubus Stygian Fury [[D2 Baal\|Template:D2 Unique bold]] (Chamber) [[D2 Uber Baal\|Uber Template:D2 Unique bold]]
	Cloak of Shadows	Assassin Shadow Warrior Shadow Master
	Confuse	Necromancer
	Taunt	Barbarian
	Decrepify	Necromancer Oblivion Knight Template:D2 Unique bold (Throne)

Overlay	Curse	Native Source(s)
	Defense Curse	Succubus Stygian Fury Template:D2 Unique bold (Chamber) Uber Template:D2 Unique bold
	Dim Vision	Necromancer Raven Hit Blinds Target
	Grim Ward	Barbarian
	HCMF	Item
	Howl	Barbarian
	Terror	Necromancer
	Iron Maiden	Necromancer
	Life Tap	Necromancer Oblivion Knight
	Lower Resist	Necromancer
	Weaken	Necromancer Oblivion Knight Stygian Fury

When same curse is cast on a cursed target, it will normally overwrite the previous cast if the skill level is equal or greater. Exceptions are Attract, Cloak of Shadows, Confuse and Howl, which cannot overwrite themselves and must expire before they can apply to the same target again (although in the case of Cloak of Shadows, only when cast by the same player). [2]
when different curse is cast on a cursed target, it will normally overwrite the previous one. Exceptions are as follows: [3]
- Grim Ward can only be overwritten by Confuse and Attract
- Fleeing effects have their own hierarchy; those higher on the following list cannot be overwritten by those lower:
1. Grim Ward
2. Terror
3. Hit Causes Monster to Flee
4. Howl
- Confuse cannot overwrite itself or be overwritten by any of the following:
  - Attract
  - Dim Vision
  - Grim Ward
  - Hit Blinds Target
  - Taunt
  - Terror
- Attract cannot be overwritten by anything, including itself.
Shrines which apply a buff for a duration can also overwrite curses, and vice versa.

Cannot be cursed

[[D2 Champion#Possessed|Template:D2 Magic bold]] cannot be cursed, and neither can the following units because they are static: [4]

Animal	Construct		Demon
Blood Hawk Nest [[D2 Coldworm the Burrower\|Template:D2 Unique bold]] Sand Maggot Egg Tentacle Beast	Barricade Barricaded Door Barricaded Tower Catapult Evil Demon Hut Fire Tower	Gargoyle Trap Lightning Spire Prison Door Mummy Sarcophagus Trapped Soul Window	Festering Appendage

However, Battle Cry and Cloak of Shadows still apply.
Effects which alter AI only apply to normal and minion monsters, with the following exceptions:
- Minion of Destruction
- Oblivion Knight
- Putrid Defiler
- Suicide Minion
Cloak of Shadows will not blind these monsters but it will still apply -% Defense (although not to Putrid Defilers, since they are bosses.