What's up gamers, how are you all doing? I have to be honest with you — the last few days were absolutely hectic and I barely had a chance to even look at my PC, let alone sit down and play. Life just got in the way in a big way. But hey, we're back now and the adventure in Hogwarts Legacy continues. So picking up right where we left off — after the flying class with Madam Kogawa, the broom purchase at Spintwitches, and everything that went down in Jackdaw's Tomb — the next mission on the list was meeting up with Sebastian Sallow. This guy has been one of the most interesting characters in the game since the very beginning, always walking that line between brilliant and reckless, and this time he had something specific he wanted to show me. The quest is called In the Shadow of the Undercroft, and it turned out to be one of the coolest and most story-rich missions I've had so far. So let's get into it.
Sebastian and the Story Behind the Undercroft
To find Sebastian you fast travel to the Defence Against the Dark Arts Floo Flame in the Astronomy Wing and follow the marker down the stairs where he's waiting for you at the bottom. Classic Sebastian — lurking near the edge of the rules. He greets you, acknowledges the whole library situation where he took the blame for us without hesitation, and then gets right to the point. He tells you he wants to show you something. Something discreet. Something he doesn't share with just anyone. And off you go following him through the hall until you reach a very old and very out of place looking clock mounted on the wall around the corner. Sebastian interacts with it, holds the mechanism, and just like that a secret passage opens up right in front of you. Behind that clock is the Undercroft.
The moment you step inside and the cutscene kicks in, you immediately understand why Sebastian guards this place so carefully. The Undercroft is enormous — a long-forgotten underground chamber deep inside the castle, completely hidden from professors, prefects, and basically everyone else in Hogwarts. The architecture is ancient, the atmosphere is genuinely mysterious, and the whole place has this feeling of being untouched for centuries. Sebastian explains that this chamber was discovered not by him but by his close friend Ominis Gaunt — a blind Slytherin student who navigated his way to it using his wand alone after being tipped off by a family member. The fact that Ominis, who cannot see, was the one who found a hidden room most sighted students would never locate is honestly one of the more fascinating small details in the game. Sebastian now uses the Undercroft as a private space to practice spells freely, completely away from prying eyes. And as you take it all in, you realize this is going to become an important place in the story going forward.
Make sure you use Revelio the moment you walk in because there are three treasure chests spread around the room — one near the right wall as you enter, one in the back by some barrels, and one near a stone pillar toward the center. Easy to miss if you go straight to Sebastian without looking around, and the loot inside is worth grabbing.
Learning Confringo — The Blasting Curse
Once you're done exploring and looting, you go talk to Sebastian and this is where things get really good. He tells you that the Undercroft is the perfect place to practice spells that probably shouldn't be practiced in the open — spells that raise eyebrows, spells that professors would rather you not know. And then he offers to teach you one. The Blasting Curse — Confringo. Now the game gives you two dialogue choices here: one where your character expresses some hesitation about how dangerous it sounds, and one where you're basically all in immediately. Honestly it doesn't matter which you pick because Sebastian is teaching you this spell either way. He's already made up his mind the moment he brought you down here.
The spell learning minigame runs and Confringo gets added to your spellbook. And what a spell it is. Confringo fires a long-range bolt of fire that explodes on impact, dealing solid damage and setting enemies ablaze — which means they continue taking burn damage for several seconds after the initial hit. It's classified as a damage spell, which means it goes into the red category on your spell bar and it's particularly effective at breaking red shield charms on enemies. The real advantage Confringo has over Incendio — which you already know — is the range. Incendio requires you to be relatively close to your target. Confringo can reach enemies from a serious distance, which completely changes how you can approach certain combat situations. You can now start fires from across a room, hit enemies before they even reach you, and keep your distance against faster or more aggressive foes. It also works brilliantly on spiderwebs if you're too far away for Incendio to reach, and it lights torches and braziers for environmental puzzles. This spell is going to see a lot of use.
To practice it, Sebastian points you toward the hanging candelabras spread around the ceiling of the Undercroft — three of them, one in the northwest corner, one to the east, and one to the south. Equip Confringo, lock on to each chandelier, and let loose. Watching them light up and explode in the dimly lit chamber feels great, and it's a satisfying way to get a real feel for the spell's power and range before taking it into actual combat.
I Tell Sebastian My Secret About Ancient Magic
After the practice session wraps up and you return to Sebastian, the conversation takes a genuinely meaningful turn. Sebastian mentions his sister Anne — his twin — and how much she means to him. He's clearly carrying something heavy around her situation, though he doesn't go into full detail just yet. He mentions wanting to go back to Feldcroft, where their family is, and that his pursuit of certain knowledge is tied to helping her. It's a window into why Sebastian operates the way he does — always pushing past limits, always willing to bend rules — and it makes him a more sympathetic character rather than just a cool troublemaker.
Then comes the big moment: he asks about you. Specifically about the prologue, about how you arrived at Hogwarts, about what happened on the way there. And here the game gives you a choice — you can share everything about your ability to perceive and channel ancient magic, or you can stay quiet and keep it to yourself. I chose to tell him the truth. The full story. And the reaction is great — Sebastian is clearly fascinated, not spooked. He doesn't treat it like something to be afraid of or reported to a professor. He treats it like the most interesting thing he's heard all year, which honestly tracks completely with who Sebastian is as a person. Sharing the secret doesn't change the mechanical outcome of the quest, but it deepens the connection between the two characters in a way that makes the friendship feel genuine rather than just a series of quest transactions.
Once the conversation winds down it's time to leave the Undercroft, and just as you're walking out the door you come face to face with Ominis Gaunt himself — the blind Slytherin who discovered the chamber in the first place. He's clearly not thrilled about Sebastian bringing someone new down here, and the conversation with him has its own dialogue choices about whether to cover for Sebastian or tell Ominis the truth about how the Undercroft was actually found. Either way the quest completes and you walk away with 260 XP, a brand new fire spell in your arsenal, and a secret underground chamber you can now visit any time you like.
Next Up — Professor Weasley and What's Coming
So gamers, the Undercroft mission was a really solid chapter in the story and Sebastian continues to be one of the most compelling characters in the whole game. Confringo is a genuinely excellent addition to the spell rotation and the Undercroft itself is going to become an important location as Sebastian's personal storyline keeps developing — and trust me, that storyline goes to some very interesting places. For now though, the next stop is back to the main story and a new mission with Professor Weasley that's going to push things forward in a big way. Stay tuned because there's a lot more adventure ahead. See you in the next post gamers!