Don't Call Me Junior

You'll need to earn Master Relic Hunter which involves completing each of the following quest chains:

The Spirit Forge - Treasure Contract: Gutrek's Cleaver
Taking from the Taker - Treasure Contract: The Infected Orc
The Blessing of Beasts - Treasure Contract: The Thunderlord Sage
The Apexis Device - Treasure Contract: Amulet of Rukhmar
Breaching the Barrier - Treasure Contract: Explosive Discoveries
The Crystal Reborn - Treasure Contract: The Artificer

If he's not in your garrison, you can use the group finder tool to find him. Simply search custom groups for Harrison Jones.

This kinda follows the same treatment that you get with Nat Pagle. Do some exploration tasks, follower shows up --> do his 6 respective quests ---> Follower get.

In this case the first part comes from Garrison missions. which means your followers are going to play a part into getting this guy. You will notice which missions you have to do since the exploration missions are marked with a map on the left side (instead of two crossed swords, or a Spyglass, or anything else).

In terms of reference, the achievement name comes from ''Indiana Jones and the Last Crusade'', in which Indiana Jones (Harrison Ford) would always tell his father Henry Jones (Sean Connery) to not call him Junior.

""Exploration Mission Master" removed from "Don't Call Me Junior" meta achievement. UI not updated until a client patch." - Bashiok