PoE2
Mana Leech
Support
Attack, Physical
Requires: Level 1
Support Reqirements: +5 Dex
Supports attacks, causing their Physical damage to Leech Mana.
Leech 2% of Physical Attack Damage as Mana
Place into a Skill's Support Gem socket in the Skills menu to apply its effects to that Skill. You cannot have multiple copies of the same Support Gem socketed at the same time.
PoE1
Mana Leech Support
Support
Level: (1–20)
Requires: Level (31–70), (52–111) Dex
Supports attack skills that hit enemies, causing those hits to leech mana based on damage dealt.
Supported Attacks have (2–3.9)% of Damage Leeched as Mana

Additional Effects From Quality:
Supported Skills deal (0–10)% increased Damage while Leeching Mana
This is a Support Gem. It does not grant a bonus to your character, but to skills in sockets connected to it. Place into an item socket connected to a socket containing the Skill Gem you wish to augment. Right click to remove from a socket.