Super Mario

Reznor Knockdown Expansion Set

The most gear-packed, cleverly engineered expansion the LEGO Mario line ever gave us.

Brick Rated Score

4.0/5

Set 71390 · 2021

Pieces862

Minifigs4

Year2021

Set number71390

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The verdict

The spinning Reznor platform is what got me, four fire-breathing dinos on a rotating fortress wheel that you flip by turning Mario on a stand, and it actually works.

This is easily the most intricate build in the whole LEGO Mario range, with gears and mechanisms tucked in all over the place. I'll be straight with you though, it does nothing on its own: you need a Starter Course and a Mario or Luigi figure to make any of it come alive. If you already have that, this is the expansion to get.

Best for: Kids who already own a LEGO Mario Starter Course and want the most mechanical, feature-rich course to play on

The full review

What it is

The Reznor Knockdown recreates one of the most memorable fortress fights from Super Mario World, the four fire-breathing dino heads perched on a spinning platform that you have to flip to knock them off. LEGO built that whole idea in brick form: a big rotating wheel that you turn by twisting Mario on a connected stand, with the two Reznors clinging on and Blue Toad waiting to be rescued at the top. The first time I turned the dial and watched the whole thing rotate, I grinned. There is something so right about a set that captures a specific game moment this faithfully instead of just slapping a character on a baseplate.

The catch

Now the practical stuff you need to know before you buy, because it matters here. This is an expansion set, not a standalone toy. Out of the box it will not do a single interactive thing. You need a LEGO Mario Starter Course (71360 or 71387) and the electronic Mario or Luigi figure that comes with it, and neither is included. If you already own one, brilliant, this slots straight in. If you do not, this is not where you start. On top of that, the original $69.99 price felt slightly high for an expansion, and the little Grrrol seesaw, where the rolling enemy trundles back and forth as Mario hops for coins, is prone to sticking mid-play, which is the one part of the build that let reviewers down.

Who it's for

So who should grab it? Anyone whose kid already lives in the LEGO Mario world and wants the biggest, most mechanically interesting course to add. At 862 pieces this is one of the largest Mario expansions, and it earns that size with genuinely clever building throughout. It also happens to have real presence on a shelf when it is built, so it does not look like a pile of loose ramps between play sessions. Skip it only if you do not own a Starter Course yet, or if you are after a display piece rather than a play set, because everything good about this box is open uped through actual play with the electronic figure.

The parts story

What the build is actually like, and the pieces worth knowing about.

Building this is the closest LEGO Mario gets to feeling like a proper Technic-adjacent puzzle. There are gears everywhere, and the rotating fortress wheel in particular is a lovely bit of engineering that hides its mechanism inside the structure so the finished thing just works when you turn the dial. Reviewers consistently called it the most intricate and most fun build in the whole Mario line, and I agree, it never drifts into the repetitive brick-laying that some of the simpler courses fall into. The seesaw section and the Speed Run pipe give you a few distinct sub-builds so the pace keeps changing.

The real draw for parts is the interactive character line-up rather than rare printed elements: two Reznors, the rolling Grrrol, and Blue Toad, all of which are specific to this style of Mario set and read as code the electronic figure responds to. You also get a ? Block and the Speed Run pipe for reconfiguring how you play. For 862 pieces at its original price, most reviewers pegged this as one of the best value expansions in the range, precisely because you are getting a mechanism-rich build plus four characters rather than a thin ramp set.

Fun facts

01Reznor is a fire-breathing, Triceratops-like enemy from 1990's Super Mario World, where the four of them sit on a rotating platform in fortress levels, exactly the moment this set recreates.
02The set was released on August 1, 2021 and retired on July 31, 2022, giving it a fairly short one-year shelf life.
03Nothing in the box lights up or reacts on its own, all of the interactive play depends on the electronic Mario or Luigi figure sold separately in a Starter Course.
04At 862 pieces it was one of the largest expansion sets LEGO made for the Mario line, and reviewers rated it the most gear-packed build of the bunch.