Needed: axe, fishing
Start off by heading down towards the camera. Destroy the cracked tile using Gimli's axe and build a bridge from its parts.
Now you need to catch a fish and throw it at the sign in the north-west. That will cause a path leading through the marshes and to the Minikit to appear.
Once again you will have to hit a couple bricks. This time they are broken tiles:
#1 - At the very beginning of the level; you need to head to the lower-right corner of the island.
#2 - By the first wall of fire in the upper left part of the island.
#3 - By the third wall of fire, to the right of the pond.
#4 - To the left of the road leading to the fourth wall of fire.
#5 - On the road leading to the large skeleton.
Treasure: Wooden Bucket
This item is needed to finish the mission and you will receive it automatically during the story mode. It's buried at the very beginning, before the first wall of fire.
Needed: elven rope
By the third wall of fire you have to head to the southern part of the island, towards the camera. There you will find leaves floating on the water - just jump onto them and keep following the path. At its end you have to use the rope and pick up the chest.
On the island before the first wall of fire, to the left of the giant skeleton you should see a cage with an orange handle. Use Shagrat's strength to open it and head further to the left to get the chest.
By the sixth wall of flame. To the left of the pond you should see LEGO Morgul bricks - destroy them using the sword and a boat will appear. You will need to backtrack a bit and collect two bones to build a bone wheel. Hand it over to the ghost to receive the chest.
Treasure: Fancy Umbrella
On one of the islands on which you hide from the Nazgul, you will see a target on the tree. Shoot it and pick up the treasure.
After another game of hide and seek with the Nazgul, in the distance you should see a tree built of LEGO bricks with a target on it. One shot and another Minikit will be yours.
After getting past the "swing", in the distance you will see another tree with a target. Hit it and ghosts with targets will start appearing to the left of you. Shoot at them all (three in total) to receive the chest.
Treasure: Toy Snake
As you reach the section with the bridge and rope hook, you will have to move a bit towards the camera. You should see a mithril barrel which you have to blow up with the Berserker's bombs. Pick up the treasure afterwards.
By the end of the escape from the Nazgul you will have to approach the wall and destroy some bushes there. Afterwards grab the handle with Shagrat and open the passage to the chest found further to the right.
Design: Mithril Stud Mallet
You need to start fishing on the bridge beside Minikit #8. That way you will receive a key with which you need to go left of the place where you need to put a plant. Open the chest and pick up the Design.
During the fight with the Mumakils, you need to head to the lower left corner of the map. Just dig up the loose ground to receive the Minikit.
Also during the fight with the Mumakils; you need to choose a character armed with a bow and destroy 5 targets appearing around the location. I'd recommend getting as close to them as possible before shooting to increase your chances of hitting. After destroying the last target, you will receive the chest.