This ability benefits from and triggers all effects associated with Heroic Strike. 20 Rage Head to Ratchet and talk to Kilxx by the docks. Purchase a Fishing Harpoon and head into the bay and find ...

Level 20 is required. The vendor named Grizzby (Ratchet) will give you tasks to bring him items (see below). Fetch those items and you will be able to purchase the rune from Grizzby for 5 Gold.