The Small Cave Shrine is on the northeast side of the lake. Look for the symbols to know what buttons to press to get in and get the Blasphemer’s Head.

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The Small Cave Shrine is on the northeast side of the lake. Look for the symbols to know what buttons to press to get in and get the Blasphemer’s Head.
To open the door in the Large Cave Shrine in order to get the Apostate Head, you have to find the three symbols in yellow paint around the cave. The order doesn’t appear to matter. I’ve entered them in different orders twice.
I have found 5 Wayshrine Locations in the game.
The Key can be found at the end of the Mural Cave, just before the boat.
In Chapter 4, after picking up the Wayshrine Key at the Mural Cave, you can get a request to find a Golden Egg. The egg itself can be found on the east side of the lake.
As you enter the Quarry, you’ll see another request to destroy Medallions. Shooting them all will get you 4 Spinels.
1. One in the open quarry area. Look up at the scaffolding.
2. One under the dock.
3. Inside the first building down in the muck. It’s hanging from the ceiling.
4. In the middle section, hanging under the left side upper ledge.
5. From Hexagon Piece B, turn around 180 degrees.
Behind the church is a request to destroy a couple of grave emblems.
In the Abandoned Factory, there is a Request Notice for Pest Control. It’s to the right of the Merchant. The 3 rats are back the way you came. Two in the last bit of the hallways and then 2 outside.
There are 5 Medallions at the Farm. Shooting them all will get you 3 Spinels.
1. Backside of the typewriter building.
2. Inside the middle barn. I got it through the southwest window.
3. Inside the rafters of the west building.
4. East two story building, hanging in an upper window.
5. Behind the Wayshrine in the gated area. Go through the windmill to get to it, and it’s hanging from the windmill balcony when you jump down.
This is a video that shows HOW to solve the puzzle in case you were like me and just fiddled with it for a bunch at first, not realizing you can solve it in just a couple of steps if you do it right from the start, and now it’s all messed up and you don’t know what to do next and you can’t reset it and you saved waaaaaaaaaay too long ago to want to reload, but you want that treasure!!
This is a map of all 95 Merlin Trials. The numbers correspond to the table below the map as well as the video number in the Merlin Trials Playlist on my Youtube Channel: Merlin Trials Playlist
Note that all of these are also listed with region in the Google Workbook.