Minikit #1: As the level begins, you can see three targets attached to poles in the background. Switch to Legolas and fire an arrow at each one to receive a minikit reward.
Minikit #2: A minikit is buried in the northwest corner of the battlefield. Use Sam to dig it up.
Minikit #3: After the battle, you’ll be on the side of Mount Doom. Toss Gimli at the cracked wall to reveal a dark cave.
Use Frodo’s Glowing Phial to enter a whole secret volcanic area. In the northwest corner you’ll see a rope hook. Use Sam’s rope to ascend to a ledge, then jump over the small gap.
Smash the rock with Gimli, climb the wall with Gollum, and finally smash the Morgul block with Aragorn.
This reveals a minikit in the pool below. Hop down and grab it.
Minikit #4: This minikit requires you to break five Morgul statues using Aragorn’s ancient sword. The first can be found in the center of the hidden volcanic area at the start of the level.
The second statue can be found just after the fire-spitting caves.
After the group of Orcs attack from the small cave, ascend the ramp to find the third statue.
The final two statues can be found on either side of the massive gate near the level’s end.
Minikit #5: Proceed through the level until you reach two small caves that shoot fire. Toss Gimli at the cracked rock to destroy it, and use the build action to plug the first cave.
Switch to Legolas and fire an arrow at the rock target. This will drop it down and plug the second cave.
The caves will shoot flames one final time and destroy the rocks you just placed, but they’ll also release pieces of a minikit. Use the build action to assemble the collectible then grab it.