Physical damage done reduced by X and healing effectiveness reduced by 20%.
Duration: 2 minutes
Hex of Weakness was one of the priest racial abilities available only to trollpriests. It allowed priests to place a curse debuff on a targeted enemy, weakening their damage caused and reducing the effectiveness of healing spells on the target by a set amount.
This spell can be obtained by Troll Priests through the quest [Hex of Weakness], which becomes available at level 10. However, troll priests can simply purchase the ability from a priest trainer should he or she choose to level in Tirisfal Glades, Eversong Woods, or Mulgore.
This debuff is actually considered a curse and can be removed by a Mage's [Remove Curse] spell.
Tips and tactics
This spell can be very useful against other priests as it cannot be dispelled, causing decreased functionality of heals and [Vampiric Embrace].
Useful against dual wielding classes as the damage reduction causes a significant amount of reduction in damage taken over longer fights. Two handed classes will see very small impact on damage done, and as such the spell is not cost effective on such classes.
Regardless of class this is still useful as it can lower bandage and potion effects which are often used in PvP (and it's usually best to have them suffer as much loss as possible). Talents/spells which improve healing on non-healers such as a rogue's Quick Recovery or a warlock's Fel Armor are also nullified, giving them only half the potential use they could have been. Also especially useful against any druid since they aren't normally expecting curses from priests.
Casting a lower rank just for the -20% healing is also a viable option if you want to save mana when fighting against non-feral druids/mages and casters in general.
In PvP situations, this debuff is not only mana efficient, but its effects are practical on all targets. By using Rank 1 of the spell, your priest not only has a cost efficient mini-MS, but at the same time, the cost makes it practical to cast on all targets.
Against shamans, the rank 1 being instant cast and costing only 35 mana makes it a great [Grounding Totem] killer.
Patch 2.2.0 (2007-09-25): No longer requires a quest and can now be trained at 10.
Patch 1.10.0 (2006-03-28): Now also applies a -20% healing modifier in addition to its normal effect. The healing debuff does not stack with the warrior's Mortal Strike ability, although the damage penalty now stacks with either Touch of Weakness or Curse of Weakness. Mana cost decreased substantially.
[Mental Agility], 
[Shadow Focus], 
[Shadow Reach]
35
[Mortal Strike], 
[Wound Poison], nor 
[Aimed Shot]; although the damage penalty now stacks with either 
[Touch of Weakness] or 
[Curse of Weakness].
[Hex of Weakness], which becomes available at level 10. However, troll priests can simply purchase the ability from a priest trainer should he or she choose to level in Tirisfal Glades, Eversong Woods, or Mulgore.
[Remove Curse] spell.
[Vampiric Embrace].
[Grounding Totem] killer.
Patch 3.0.2 (2008-10-14): Removed. 
Patch 2.2.0 (2007-09-25): No longer requires a quest and can now be trained at 10. 
Patch 1.10.0 (2006-03-28): Now also applies a -20% healing modifier in addition to its normal effect. The healing debuff does not stack with the warrior's Mortal Strike ability, although the damage penalty now stacks with either Touch of Weakness or Curse of Weakness. Mana cost decreased substantially. 
[10] Hex of Weakness
