How To Complete The Runner's Wild Relic Ruin

Finding the Altar Key:
First off, approach the ruin from the west. You'll spot a locked door on your left – that's our goal. To get there, hop into the small room on the right. Use your Igniter on the Firegleam Wall, and then blast it open with your Pullcaster. Head through the opening you just made. You'll see a crate; use your Pullcaster to pull it towards you. Grab it (press [Triangle]) and push it through the two holes you've created. Keep pushing it to the end of this path and then climb up onto the roof. Now, push the *other* crate you see down to the ground floor. Drop down yourself and look behind you for a Grapple Point. Break that open, and then drag the crate you just pulled down over to the other crate. Drag this combined setup to the opposite side of the area and place it inside the tower. Climb up from there, and you'll find the Altar Key.

Finding the A Church? Really? Ornament:
Now that you've got the key, unlock the door. You'll need to break down the wall to your left using your Pullcaster. Place the crate you find in front of this hole, and then pull the top crate into the room. From here, push this crate to the end of the slope. Climb into the hole in the tower, and you'll find the A Church? Really? Ornament.