What the achievement asks
Kill twenty pirates at the Port of Zem'lan while Ol' Bonebite is following you. Five points, account-wide, both factions.
The killing is trivial. The whole achievement is getting Ol' Bonebite to show up, and that is where people spend an evening without understanding what they are missing.
How Ol' Bonebite is summoned
Three kinds of object lie around the port, and each gives you a ten minute buff when you interact with it:
- Pirate Hat, gives Thirst for Adventure
- Zem'lan Blackeye Brew, gives Thirst for Brew
- Treasure Map, gives Thirst for Treasure
You need all three buffs at the same time. Hold them together and Ol' Bonebite appears on his own and follows you like a pet, for as long as they last.
That is the trick, and nothing in the achievement text says it. People collect the objects one at a time over an evening, let the first buff expire while hunting the third, and never see him.
Where they are
The three types are grouped, roughly: hats in the centre and south-west, brew in the south-east, maps in the north.
At least one of each type is up at any moment, so you never have to wait. Objects of the same type share a respawn, meaning that taking one makes another appear elsewhere on the list rather than leaving you short.
They sparkle now, which they did not at launch. If you are following an old guide that says to hunt them with your bare eyes, ignore it.
Losing him
The buffs are what hold him, so you lose him if any of them runs out, if you die, or if you leave the port. Collect the three close together, then start killing immediately rather than exploring.
The port also applies Eternal Curse of Zem'lan, which increases the damage you take by ten percent. It changes nothing at current levels, but it explains why the pirates hit harder than they look.