Chain Champ Achievement in Skylanders Giants
Chapter 2 - Complete the Chain Pull Feat of Strength
How to unlock Chain Champ
The chain pull feat of strength is found after you are introduced to the Drow Lance Master. After the cut-scene, walk to back and left. Use a Giant Skylander to toss the boulder aside, and move to the giant chain and press until done.
Here's a video by XboxAchievables: