Find 3 Artifacts in Mountain Temple

This mission is obtained from Onin.

After meeting Onin, she'll ask you to find three artefacts in the Mountain Temple. Head to the marker on the map and progress into the mountains, and you'll find three paths you can follow. It doesn't matter which order you go in, but here are a few things you should look out for on each path:

Left Path: You'll encounter a shield-bearing Metal Head. Wait for it to lower the shield, then take it out. Another will appear soon after, but when you traverse to where he was the ground will break up and you'll need to make use of a few platforms. After that there'll be more platforming and baby Metal Head attacks, simply use your shotgun to take them out as usual, and pick up the left-behind Gems.

Middle Path: This path leads to a roofed structure. Follow the platforms outside one of the exits and you'll encounter a rhino Metal Head. Roll around the place, and when it roars, go crazy shooting it. Eventually you'll come across a high cliff with many rocks crashing down. You have to climb this summit whilst dodging the rocks. Traverse a little more and you'll finally find the artefact.

Right Path: There'll be a massive slew of baby Metal Heads which will attack you when you climb up the hill. Soon after you'll meet a Metal Head bearing a shield. Wait for it to lower the shield, then shoot him, he doesn't take long to kill. After a bit of platforming you'll come across a box puzzle in a Dark Eco pool; hit the boxes in the following order (assuming the other side is north):

Box 1: Front, Left, Front, Front, Left
Box 2: Left, Front, Front, Front, Left
Box 3: Front, Right, Right, Right, Front
Box 4: Front, Front, Right, Front, Front
Box 5: Front, Right, Front, Front, Right

At the end you will encounter another rhino Metal Head, and then you can collect the artefact.