Serpent Spine Longbow

Serpent Spine Longbow is an epic bow.

Source
This item drops from Lady Vashj in Serpentshrine Cavern.

Patch changes
This bow was upgraded to Item Level 141 in patch 2.2. It gained 3 minimum damage, 6 maximum damage, 1.5 DPS, 2 stamina and 1 critical strike rating.