Phylarch the Evergreen

If you cut down 3 large timber and successfully beat him 3 times, he will determine you are much superior than he and become your follower.

The quest chain to acquire the follower [follower=194] for your garrison starts when you upgrade your lumber mill to level 3.

When harvesting one of your first Large Timber, Phylarch will pop out and try to defend the tree. This will happen somewhat randomly until you fight and defeat him three times; he then decides basically "if you can't beat 'em, join 'em" and offers to become your follower.

At your garrison he is most commonly assigned to the lumber mill, where he processes the trees "more humanely" and increases your mill's output significantly. He will also offer a dungeon quest for The Everbloom (normal or heroic) which rewards you with [item=117398] - it turns you into a powerful nature creature for one minute to attack your enemies.

Edit: Grammar.

Refers to the player as "master" or "mistress" rather than Commander.