Leech (Necromancer)

Leech is a Curse skill in Diablo III. Its role is similar to the classic Life Tap: to grant the Necromancer Life from enemies upon damaging attacks.

In-game
When activated, this skill curses the ground within the targeted area for 1 second. Any enemy touched by it will be cursed for 30 seconds.

An enemy that is cursed with Leech will heal a player and their minions when the player attacks it.

Leech functions differently to Life on Hit. Instead of healing the player for 2% of their maximum health with each attack/cast, the amount of healing received scales with the Proc Coefficient of each skill and the number of cursed enemies hit.

Healing from Leech is not shared between players. Each player heals themselves from their own attacks made against a cursed enemy: however, all players, of any class, can gain healing from enemies the Necromancer curses with Leech.

Unlike Diablo II Curses, in Diablo III multiple curses can afflict the same target.

Runes

 * Transmittable: Cursed enemies will spread the curse to a nearby unaffected target when they die, with the same remaining duration.
 * Osmosis: Each cursed enemy increases the Necromancer's Life regeneration. The amount per enemy scales with level, up to per second per enemy at level 70.
 * Blood Flask: Whenever a cursed enemy dies, the potion remaining cooldown is reduced by second.
 * Sanguine End: Whenever a cursed enemy dies, the Necromancer is healed for of current Life per Kill (effectively triples the Life per Kill statistic).
 * Cursed Ground: Instead of applying the curse for 30 seconds to enemies in the area, curses the ground itself, healing the Necromancer for of maximum Life every second for each enemy in the cursed area. No longer awards Life on attacks and no longer applies an actual curse effect to enemies. Only one area can be cursed at a time.

Non-rune enhancements

 * Cursed Scythe: Enemies hit by the Scythe have a 15% chance to be inflicted with a random Curse of the Necromancer's arsenal; these curses do benefit from runes and enhancements, if any.
 * Trag'oul's Corroded Fang (Legendary Scythe): The Cursed Scythe rune gains a 100% chance to apply a curse and increases damage against cursed enemies by 175-200%.
 * Spear of Jairo (Legendary Spear): The Necromancer's is increased by 10-15% for every enemy afflicted by a Curse.
 * Briggs' Wrath (Legendary Ring): Uncursed enemies are pulled to the targeted location when a Curse is applied to them.
 * Dayntee's Binding (Legendary Belt): the Necromancer gains a 40-50% reduction to all damage taken while Leech is active on at least one foe.
 * Cursed Form: While active, Simulacrum makes all Curse skills apply all three curses to each target, even if the Necromancer does not have the other two Curses on their skill set.
 * Trag'Oul's Avatar Set (Set Bonus for 4 items): while at full Life, healing from skills is added to maximum Life for 45 seconds, up to 100% additional Life.
 * Trag'Oul's Avatar Set (Set Bonus for 6 items): healing from skills is increased by 100%.

Passives

 * Eternal Torment: reduces Essence cost by 50% and increases duration to 5 minutes. Has no effect on Cursed Ground rune.
 * Spreading Malediction: Increases the Necromancer's damage done by 1% for every enemy afflicted by any Curse.

Development
The reason that there is no cooldown on Leech is that the lack of a cooldown is justified from a cost/benefit perspective.