This guide will let you know how to do the Merlin trial in Keenbridge in Hogwarts.
When you start the trial, you will find a large Boulder in the middle of the field just behind the woman who runs a market stall. You need to do is use your normal attacks using R1 and when you get the big hit at the end, it’ll push it over.
When it gets stuck, use your R2 or right trigger and keep doing your basic attack until you get the combo off. It will clear it out but it can reset if it goes too far. So it is more reliable to use the wand attack rather than the Spells. Just use your attacks to take it on the platform and complete the puzzle.