Drain Life

Drain Life
Drain Life 30 yds. range 17% of base mana Channeled Drains the life from the target, causing X Shadow damage and restoring 2% of the caster's total health every 1 sec. Lasts 3 sec.
Usable by
Class	Warlock
Properties
Type	Offensive, Defensive
School	Shadow
Cooldown	None/Global Cooldown
Talents
Improvement talents	Soul Siphon, Grim Reach, Shadow Mastery, Fel Concentration,
Related debuff
Magic Drain Life Drains X health every 1 sec to the caster. Duration: 5 sec

"Tonight, I'll drink to your health—may it long be mine." ^[1]

Drain Life is a warlock ability that damages the targeted enemy's health while restoring his own.

Table[]

This spell works well with +Shadow Damage gear. If you combine a lot of +Damage gear with maxed ranks in Soul Siphon and Improved Life Tap you can significantly increase your net gain in mana when you Life Drain to regain what you lose with Life Tap.
Because Drain Life deals damage and heals, it receives a 50% penalty from +damage gear. The total bonus is then distributed amongst the five ticks of the spell. For example - if you have +100 spell damage, each tick of Drain Life will transfer +10 HP from the target ((100*0.5) / 5).
Drain Life combined with Life Tap can allow a Warlock to act as a tank.
In Patch 2.3, the amount healed is reduced when the warlock is affected by healing reducing effects (e.g. Mortal Strike, Wounding Poison).
Demon Armor will allow the warlock to gain more health from the heal in the same way Mortal strike effects reduce the amount of healing done by the spell.