The feats and your progress can be tracked via the pause menu. Complete the following feats:
Feat: Inventions inbound!
Description: You need to find the 3 Stark Tech Packages.
Reward: War Machine Costume
The first piece is found in the Headquarters and can be obtained after the Olympus level. Just walk into the doorway on the right to get to the next screen. You will see a closed grey door in the background. Walk through that door and into the back corner of the next room for the package.
The second piece is found in episode 5. After you complete the first parts of the game show, you will find yourself in a top down view similar to Gauntlet. Use Wolverine to slice through the first door and you should see the blue glowing object in a room off to the left. Work your way through the maze to the second door and use Wolverine again to get inside and collect the package.
The third piece can be found in episode 4, “Time to Find Time” in Free Play. After you fight Annihilus for the first time and he runs away you exit the throne room via the left door. In this next section you need to clear out all the minions and then fix a green machine with elemental power to move on. Right beside that first green machine is a computer terminal in the back wall. Once all the enemies are dead, hack the terminal and a hole in the wall opens up and shoots out a couple of time gems and the final piece.
Feat: Power stone fragment
Description: Collect 100 Power Stone Fragments
Reward: Challenge map - Asteroid Field
These fragments are found on episodes 1 (both parts), 8 and 10. You get fragments by killing enemies, destroying objects and finding secret areas. You can replay the levels via Free Play until you get the required amount. While in Free Play, you will be able to freely swap to any character type you need by holding down the button and then pressing up or down until you get to whoever you want. You can check your progress in the fragment display room found in your headquarters.
Feat: Stark certified
Description: Complete all previous feats.
Reward: Achievement unlocks.
This unlocks automatically when you complete the other 2 feats.