Marunweem Lake Infamous Foe counts as one of the Hogwarts Legacy side activities required to get 100% completion in the southeastern lake area featured in the Harry Potter-inspired video game published byΒ Warner Bros. Games.
Unlike other formidable enemies, the Marunweem Lake Infamous Foe in Hogwarts Legacy canβt be found in the open world, meaning youβll have to look for him in a dungeon. Furthermore, the Hogwarts Legacy Foe in Marunweem Lake is pretty well hidden, and he can be easily missed if you rush through the said dungeon.
Where To Find the Marunweem Lake Infamous Foe in Hogwarts Legacy
The Infamous Foe in Marunweem Lake is found in The Coastal Mine dungeon; youβll get to explore while playing Lodgokβs Loyalty main quest. The Coastal Mine is a high-level dungeon found on the northern side of Marunweem Lake, as you can see on the map below.

If you intend to visit this area while playing the associated quest, itβs recommended to check our Lodgokβs Loyalty walkthrough, which also covers all Treasure Chests locations. Furthermore, you should know there are two Coastal Mine Collection Chests youβll also have to find inside the dungeon.
Assuming you missed the Infamous Foe during your first visit, head to the Coastal Mine Floo Flame, then enter the dungeon again via the iron door on the right side of the vast tunnel. Once inside, youβll want to progress through the first section and take the Goblin Cart to the lower floor.
Now, keep following the linear path and use Accio to move the platform and cross the large gap. Next, youβll reach the largest hall in the Coastal Mine, and once again, youβll need to remove the Goblin presence.
After the hall is clear, check the northern side, and youβll see a storage deposit. On top of the stairs is a furnace (pictured below) that youβll have to ignite by casting Confringo.

By igniting the furnace, youβll activate an elevator on the lower level (also marked above). Get on the elevator and interact with the mechanism to reach the ground floor of the storage area, where the Marunweem Lake Infamous Foe named Grodbik awaits.
How to Defeat Grodbik
Grodbik is a Level 34 Goblin protected by a red shield, so you must cast Damage Spells on him. However, there is a fast method to deal with this mini-boss, which is also quite amusing. If you completed Sebastianβs In the Shadow of TimeΒ Side Quest and unlocked the Imperio Unforgivable Curse, you can easily cast it on the Fortified Troll protecting Grodbik, and heβll deal with the boss. The Fortified Troll deals heavy damage while also taunting Grodbik.

Once he defeats Grodbik, cast Imperio again on the same Troll, and heβll clear the storage deposit for you. Finally, youβll have to defeat the Fortified Troll, which is the same as the Trolls you encountered in front of the Coastal Mine entrance.