Merlin Trials are scattered throughout the highlands surrounding Hogwarts. They serve as decoration until you intervene in Ashwinder heavies interrogating Nora Treadwell near Lower Hogsfield. Once unlocked, the first 52 trials you complete give you 80 experience points toward your character level.
The Merlin Trials quest instances after completion of Professor Hecat's Second Assignment. Natty will ask you to travel to Lower Hogsfield, south of Hogwarts. When finished with her concerns, you happen to be nearby Nora's campsite when Ashwinders show up to harass her. As it turns out, they are looking for you, and she happens to be handy where you were last seen, … right here in Lower Hogsfield! Events play out, and Nora can let you into her research, the mystery of the various mechanisms of the Trials of the famous Merlin.
There are several varieties of trials. Each has a swirl, a stone pattern that activates the trial when exposed to the herb mallowsweet. Once activated, the active state is maintained for a certain amount of time. It is possible to activate a trial, leave, and come back several hours later. In order to complete the trial, you have to use the spells you have learned to best complete the forms. If you do not have a necessary spell, you must attain it before completing the trial.
Sinking Pyres- The case you discover first. Three pyres must be lit with either Inflamarae spell before any pyre drops below ground level and extinguishes, resetting them all. Obviously, Confringo gives the advantages of speed and distance.
Merlin's Hopscotch- A set of platforms that, once you step upon the first, you must not step on the ground or any other surface until stepping on the last. Doing so resets the trial. Some Hopscotch trials can be accomplished with a broom, but not all.
Targets- A set of nine balls on pedestals, arranged about the swirl, and occasionally behind other items. You need only destroy all the spheres with any attack.
Firefly Moonstones- Three blocks containing a chunk of moonstone and three clouds of fireflies. The fireflies will follow a Lumos-lit wand. If doused for too long, the fireflies usually return to where they began, though they can disappear, requiring returning later after moving far enough away for the trial to reload. It’s very common for the fireflies to be gathered behind obstacles, and to have to carry them up and down rocks and steps that may douse your wand.
Magnetic Marbles- Accio can summon objects to you. The magnetic marbles share their summoning amongst the five members. It is then only necessary to draw the one you call over a nest, a stony disk with four depressions in a square. The settling of the first calls the rest to complete the stack, and the nest.
Repair Statues- Activating the trial causes three statues (or four in a single case) near the swirl to break apart. It is necessary to cast Reparo on each to complete the trial.
Merlin's Golf- Put the ball in the cup. Though the ball is over a meter wide, slightly less than round, and the cup is a bowl over two meters across, it barely catches any fast-moving ball. Basic cast can move a ball, but it's often useless. Depulso is the best mover, and control spells can interrupt out-of-control balls. A ball that leaves the fairway will disappear and reset to the start. Some of the balls can be lifted with Wingardium Leviosa, making it much easier to hole in one by walking the ball straight to the cup, assuming the course allows it.
Demolition- This is a large-scale version of Targets using five monoliths. A minimum of Confringo is necessary to pulverize the stones, though Bombarda can be used instead.
Dice Match- Three dice on three squared pillars. The dice must be turned to match the icons on the four pillar sides with the dice sides. The spell Flippendo is the only way to roll the dice.