From WoWWiki

Drain Life
Drain Life channeled sec cast 30 yds. range 425 Mana Transfers X health every 1 sec from the target to the caster. Lasts 5 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,
Other Information
Ranks	8
Related Buff
Magic Drain Life Drains X health every 1 sec to the caster. Duration: 5 sec

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

Rank	Mana Cost	Damage	Level	Cost
1	55	10	14	8 10
2	85	17	22	22 50
3	135	29	30	54
4	185	41	38	90
5	240	55	46	1 17
6	300	71	54	1 80
5	355	87	62	2 70
6	425	108	69	6 30

Notes

• 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 does not benefit from +healing.
• In Patch 2.3, the amount healed is reduced when the warlock is affected by healing reducing effects (e.g. Mortal Strike, Wounding Poison).
• Fel 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.

Playable Classes
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