Serpent's Tongue Rune (IV)

+50% Strong Attack Damage.

Piercing Lunge costs half as much Mana.

Piercing Lunge inflicts Vulnerable, and each cast reduces the cooldown of a random Special ability by 1 second.

Each cleared boss encounter of level 40 and higher has a 2% chance to drop a rune (1.5% on mini-boss stages). On Inferno 0.5% of those runes are Set Runes before the stage's loot bonus and Item Find, which raise it; on Normal and Nightmare no Set Rune drops. Only runes for the current hero's class drop.