This guide will let you know how to complete the Merlin trial puzzle in Hogwarts Legacy.
You can find it near the Forbidden Forest, you will find one with the three pillars that have the Moonstone sort of gems inside it.
You have to put down the plant on the circular platform to start to trial and you will find a group of blue butterflies there. Use the light spell on your wand to gather them up.
There are a total of three sets, one near the tent, one near the tree and the last one near the bench. Once, you get a set, you need to head back to the rock.
The challenge will be completed once you take all three sets to the rock.