You need to omplete the following achievements:
Aquatic Assault
Critical Critters
Elemental Escalation
Humanoid Havoc
Mechanical Melee
Beast Blitz
Draconic Destruction
Fierce Fliers
Magical Mayhem
Unstoppable Undead
You will receive Felclaw Marsuul pet.
Here you can buy Family Fighter achievement for EU or US Servers.
You'll get guide for completing Family Fighter achievement
