In Act 1, you'll find a trader who has a puzzle box that he can't open. To get the trophy, you need to kill the warrior character while trying to solve the puzzle.
Each of the three wheels controls one part of the mural. The red wheel controls the monster, while the blue wheel controls the warrior. The yellow wheel controls the spear in the middle. The grey button in the centre makes everything move. Each wheel has an arrow on it pointing to one of the four actions. Top left is to stay still, top right is to move towards the centre, bottom left is to move away from the centre, and bottom right is to raise or lower the spear.
For the first action, move the red wheel so it is pointing bottom left. Move the blue wheel so it is pointing to the top right and leave the yellow wheel so it is pointing bottom right. Press the grey button. For the second action, leave everything where it is and press the grey button again. The spear will impale the warrior and everything will be reset.
The video below first shows how to get the trophy before completing the puzzle properly.