Class

Warlock

Soul Leech · levels at 2 / 4 / 6 different pieces

Every Warlock piece: At battle start, a Warlock at full HP gives up 25% of its current HP to gain +50 mana (max 100).

Lifesteal works on all damage (attacks and spells), except Monk Drunken Stagger and Draenei (4) damage.

2
All allies heal for 5% of all damage they deal.
4
All allies get +20% more lifesteal (25% in total).
6
Warlocks steal max HP equal to 50% of all damage they deal: the target loses that much max HP and the Warlock gains it.
Note: The tooltip says on every attack. It works on all damage, including spells.

Official in-game tooltip

Warlock pieces convert 25% of their health into 50% mana when a battle starts.

Class Perk: Soul Leech
Active when you have at least (N) different Warlock pieces on board. (Multiple effects stack)

(2) Warlocks: All allies have All allies have +5% lifesteal from all damage dealt.
(4) Warlocks: All allies have All allies have +20% lifesteal from all damage dealt.
(6) Warlocks: All ally warlocks steal a max health of 0.5x damage on every attack.

Warlocks are cursed sorcerers who use demonic power to drain the life force from their enemies, restoring themselves to continue their cursed battle.