Trials of Merlin
In this walkthrough for Hogwarts Legacy, we'll give you the complete tutorial for the main quest: Trials of Merlin.
Once you've finished your chat with Natty, you'll hear screams coming from Nora Treadwell, who appears to be under threat from enemies. Go to her aid.
Use your spells to attack the Ashwinder Scouts and to defend yourself. A Ashwinder Duellist will appear, so keep using your spells to attack and defend.
Once all the enemies have been defeated, head for Nora Treadwell. She'll tell you about her research into Merlin from the legend of King Arthur. She explains that Merlin studied at Hogwarts and is interested in the strange installations he left there centuries ago.
The strange installations she mentions are vegetation-covered pillars scattered all over the place. They're called "Merlin's Trials". To activate them, you need an ingredient called "Mallowsweet". According to Nora Treadwell, this is an essential ingredient for activating the Trials. The sweet mallow must be placed in the center of the symbols.
Once the discussion is over, head for the chest to collect the Mallowsweet and place it in the middle of the round symbol.
To complete Merlin's challenge, simply cast the Incendio spell on the 3 pillars that appeared after depositing the Mallowsweet in the center of the round symbol. Once you've completed the challenge, talk to Nora.
It's important to note that completing the various Trials of Merlin is a great thing to do as soon as possible from this point onwards, as the rewards from these trials increase your inventory capacity. This will allow you to destroy/sell/manage your inventory much less often than before.
And so the quest: Trials of Merlin comes to an end, making way for your next main quest in Hogwarts Legacy: Richard Jackdaw's Ghost.