December 7, 2023
Polyjuice Potion Mistake (76386)

Polyjuice Potion Mistake (76386) Review

Summer 2021 brought with it a new wave of Hogwarts sets from the Harry Potter theme. For the last several years, the Hogwarts sets focused mainly on large interconnecting sections of the castle. Consequently, we saw the Whomping Willow, Great Hall, Clock Tower, and Astronomy Tower. Granted, smaller rooms came out as well. There was the Room of Requirement, as well as the Hogwarts Moments books. However, the smaller sets did not link up with the larger ones. The summer 2021 wave features small and large segments of Hogwarts. Additionally, the sets are modular, and their arrangement is customizable. But do they match the detail of the previous installments? This week, True North Bricks is taking a look at all of the new Harry Potter sets, starting with Polyjuice Potion Mistake (76386).

NOTE: The LEGO® Group provided this set for review. However, the provision of products does not guarantee a favorable review. I will use my usual rating system (click here for more information) and provide my honest opinion.

Polyjuice Potion Mistake (76386)


  • NAME: Hogwarts Polyjuice Potion Mistake
  • SET #: 76386
  • THEME: Harry Potter
  • COST: $24.99
  • BRICK COUNT: 217
  • RELEASE DATE: June 1, 2021


  • VALUE: 83% (Good cost-per-brick, but merely satisfactory build time.)
  • BUILD: 95% (Great detailing and play features for such a small set.)
  • MINIFIGURES: 93% (Lots of minifigs, but sadly they all have stumpy legs.)
  • ENTERTAINMENT: 80% (Kids get more from this set than adults, but all HP fans get a treat.)
Polyjuice Potion Mistake (76386) box contents.


VALUE: 83%

Polyjuice Potion Mistake costs $24.99 in Canada. Additionally, the set contains 217 pieces. Consequently, the cost-per-brick is $0.115. That is particularly good both compared to Harry Potter sets as well as LEGO® sets in general. By comparison, my average cost-per-brick for Harry Potter is currently $0.135, while for LEGO® sets in general it sits at $0.138. I rate the value-per-brick at 88% in this case.

“Do NOT go in there.”

Polyjuice Potion Mistake is a small set that took me 28 minutes to build. Therefore, at full price the cost-per-minute of build time is $0.89. For the Harry Potter theme, that is slightly more expensive than my average of $0.86. Compared to LEGO® sets in general, it is also more expensive than my average of $0.83. The build time here is satisfactory, but not great. I rate Polyjuice Potion Mistake at 78% in this category. Taking the average of this and the cost-per-brick score gives an overall value rating of 83%.

Polyjuice Potion Mistake bathroom secret passage.

BUILD: 90%

Polyjuice Potion Mistake is a fun little set. You build a bathroom. Specifically, it is Moaning Myrtle’s abode from the Harry Potter series. The bathroom features three sinks and a bathroom stall. The central sink flips open revealing a secret passageway underneath. For a small build, the detail in this room is nice. I like the half-hexagon sink arrangement, and every Hogwarts needs a bathroom stall. Both sides of the room feature arched entryways. If I had to nitpick, that is my issue with this set. Having one open arch is fine in case people want to expand the bathroom with more stalls. However, one side needs a proper door. No one wants to use a bathroom where everyone in the hallway outside can see you. Again, that is me nitpicking. For the price point, you get a nice build with great detailing and play features.

Harry and Ron as Crabbe and Goyle.

In terms of other downsides, I can predict one already in terms of the modular style of this Hogwarts set. Having multiple small rooms like this leads to a very boxy overall Hogwarts. If all small rooms are rectangular in order to fit together in custom fashion, you lose the interesting angles and rounded builds of multi-story, large sets. However, this is only the first section I am building of the new Hogwarts. We will see how all the sets look together at the end of this review series.

Cat-Hermione from Polyjuice Potion Mistake.


Polyjuice Potion Mistake comes with four Minifigures. One is a collectible, and not really a playable character. Each of these new sets comes with a commemorative golden Minifigure. These minifigs celebrate the 20th anniversary of LEGO® Harry Potter. The LEGO® Group did a similar collection for this year’s 10th anniversary of Ninjago. I think it worked better for Ninjago. Ninjago has a core set of characters to collect in golden form. While Harry Potter also has a core of Harry, Ron, and Hermione, there are so many other characters in the books and movies too. These supporting characters all feature more prominently at some point in the series. How do you pick the most relevant? One of the sets in this new series features Quirrell. Why him? He is in one book. There are more consistently present characters.

Polyjuice Potion Mistake (76386) comes with a commemorative Golden Harry Potter minifig.

The set comes with regular and golden Harry Potter, Ron, and Hermione. Additionally, Harry and Ron can transform into Crabbe and Goyle while Hermione turns part cat. Sadly, all of the characters come with the stumpy, non-moving legs, which costs this set a lot of points. Especially in a set with a toilet, all Minifigures need to have moving legs that allow them to sit. Otherwise, the minifigs have double-sided faces and torso prints. In terms of accessories, Hermione has a cat head to fit over her Minifigure head. Both Ron and Harry have alternate hair for their Crabbe and Goyle transformations. Additionally, the set includes four pairs of wands, a cauldron, a spoon, and a mug with Polyjuice potion in it. Finally, all of these new Harry Potter sets contain collectible printed wizard card tiles. This set has two. I rate the character design and accessories at 85%.

Four Minifigures in a 217-piece kit is great. In fact, for the Harry Potter theme, it is the best I have seen to date. Incidentally, it works out to 54 bricks per Minifigure. My average for LEGO® sets in general is 168-to-1 right now, whereas for Harry Potter sets it is 136-to-1. Either way you slice it, you get a lot of Minifigures for a set of this size. I rate that at 100%. Averaged with the design score, these Minifigures earn 93% overall.

Harry, Ron, and Hermione from Polyjuice Potion Mistake.


As an adult fan, this set is not terribly appealing to me for the kit or the Minifigures. If I was a bigger Harry Potter fan, I do think the cat-Hermione makes for a unique draw. Additionally, you acquire Crabbe and Goyle. Ultimately, the set is not a collector’s piece or a display piece on its own. The bricks are useful for custom creations though. It is hard to say if I will like this set more as part of a larger modular build. I suppose time will tell. For now, Polyjuice Potion Mistake is mostly a kid’s plaything in my books, with perhaps some interest to AFOL Minifigure collectors.

For kids, Polyjuice Potion Mistake offers a lot more. The bathroom stall is fun, as is the secret passage under the sink. Combined with other sections of the castle, the set is even better. However, this is supposed to be Moaning Myrtle’s bathroom. The set would be more complete if came with Myrtle. So far, that Minifigure only appeared in the wave two of the Collectible Harry Potter Minifigure Series. This is not the most exciting set I have ever seen for play, but not the worst either. I am comfortable giving this set an entertainment value of 80%. For kids alone, it probably scores higher.


At full price, Polyjuice Potion Mistake (76386) offers a good number of bricks for the price. The build time is a little low, but not horrible. The set also comes with a lot of Minifigures for a set of this size, and decent accessories. Additionally, the characters are likely interesting for Harry Potter collectors. I like the bathroom stall and the secret passage under the sink as play features. However, they are just that: play features. This set is a brick box for most adult collectors, I think. What are your thoughts on Polyjuice Potion Mistake? Feel free to comment below or reach out on social media.

Until next time,


This set should have included Moaning Myrtle instead of two Harry Potters.

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