Super Mario RPG: How to Find and Beat Culex – Secret Boss Guide

Don't underestimate the power of 2D, or you'll find yourself flattened.
Screenshot by Prima Games

Culex is the strongest boss in Super Mario RPG before the post-game. Here’s all you need to know to prepare for and defeat Culex.

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Who is Culex in Super Mario RPG?

Culex is a secret boss in Super Mario RPG, and the hardest boss in the game outside of post-game rematches. In the monster codex, he’s described as coming from the world of “Last Illusion,” a reference to Final Fantasy. Culex even uses the Final Fantasy IV boss battle theme during his battle. These references are included because the original Super Mario RPG: Legend of the Seven Stars was developed by Square. He’s returned in the Nintendo Switch remake and is just as strong as before.

Why Should You Try to Defeat Culex?

Victory against Culex is the only way to get the Quartz Charm, one of the best accessories in the game.

The Quartz Charm does not increase any stats but instead provides the following effects:

  • Grants the wearer immunity to instant death moves.
  • The wearer takes 50% less damage from attacks.
  • The wearer deals 50% more damage.

How to Find Culex in Super Mario RPG

Culex is hidden behind the locked door in Monstro Town, just to the left of the item shop. You can tell which door it is at a glance because it’s much darker than the others. To unlock the door, you’ll need the Shiny Stone in your inventory, which you get from Moleville.

How to Get the Shiny Stone

To get the Shiny Stone, you need to give fireworks to the small mole with a ribbon beside the five crates in Moleville. Conveniently, you’ll find the fireworks you need in the house just to the left of the little mole.

Enter the house and speak to the adult mole in overalls at the back. He will offer to sell you fireworks for 500 coins. Buy the fireworks and return to the little mole just outside to complete the trade.

If you speak to the little mole again after you get the Shiny Stone, she will ask if you want to trade again. However, if you say “Yes,” she will say it’s sold out. You can only get one Shiny Stone from the little mole.

Once you have the Shiny Stone, all you need to do is enter Monstro Town and challenge Culex. However, Culex is the toughest boss fight in the game before the post-game exclusive battles, so you’ll want to thoroughly prepare before challenging him. You can enter the door to speak to Culex and still decline his request to battle.

What You Should Do Before Challenging Culex in SMRPG

Beat Exor

This isn’t a strict requirement—you can actually challenge Culex before getting even the sixth star of the game. However, you’ll be at a major disadvantage if you try to challenge him that early on. If you want to be as prepared as possible, it’s recommended you defeat Exor before trying to take on Culex.


There’s a way to cheese the Exor fight if you’re so inclined. First, defeat the eyes to open Exor up to attack. Like in the original game, Exor is not programmed to be immune to Geno’s Geno Whirl special attack. Time the button press just right to land a critical hit, dealing 9999 damage and take Exor out in one hit!

After getting sent to Weapon World, take the springboard to return to the overworld. You’ll be around Level 20 to 21 at this point, and you can roam around the world to pick up what you need before challenging Culex.

Pick up the Weapons From the Six Door Challenge in Bowser’s Keep

After the first save point in Bowser’s Keep, you’ll encounter the six door challenge. You only need to complete four to proceed, and the stages behind the doors are randomized each time. Mallow’s, Geno’s, and Bowser’s best weapons (before the post-game rematch rewards) can be obtained here. If you didn’t get them the first time you passed through here, you can return after defeating Exor to try again until you get the three weapons. The weapons (and what kind of course you need to complete for them) are as follows:

CharacterWeapon NameAttackSix Door Challenge Course Type
MallowSonic Cymbals+70Action course
GenoStar Gun+57Battle course
BowserDrill Claw+40Battle course

Other rewards from the six door challenge courses include two Rock Candy items, one at the end of each of the Puzzle courses, and the Super Slap, Peach’s second-best weapon in the game, at the end of another Action course.

Purchase the Armor from Croco’s Second Shop in Bowser’s Keep

After clearing the six door challenge in Bowser’s Keep, you’ll pass another save point, then battle Wizakoopa. Defeat him to unlock both a treasure that never runs out of coins, and access to Croco’s second shop. In the room with Wizakoopa and the treasure chest, enter the leftmost door to meet with Croco and buy everyone’s best armor. If you’re running low on coins, return to the main room and spend some time getting coins from the treasure chest.

CharacterArmor NameDefenseMagic DefenseCost
MarioHero Shirt+48+24100 coins
MallowPrince Pants+48+24100 coins
GenoStar Cape+36+18100 coins
BowserHeel Shell+24+12100 coins

Peach’s Royal Dress is also available for 100 coins here, but you’ll want a different armor for her that you’ll obtain later.

Stock Up on Maple Syrup, Mid Mushroom, and Pick Me Up

You can purchase Maple Syrup, Mid Mushroom, and Pick Me Up from various shops around the world, but Croco also helpfully sells them at his second shop. Buy as many of each as you can hold.

Mid MushroomHeal 80 HP20 coins
Maple SyrupRecover 40 FP30 coins
Pick Me UpRevive a fallen ally5 coins

Get Peach’s Frying Pan from the Treasure Hunting Toad

When you get the third star, the treasure-hunting Toad will open up a Miner’s Store in the item shop in Moleville. After defeating the Axem Rangers, the Toad will have a strange piece of metal for sale for 300 coins. While it’s recommended you purchase all of the Toad’s inventory, you’ll definitely want the Feather, which is a helpful extra accessory to have, and the piece of metal—it’s actually Peach’s Frying Pan!

The Frying Pan is Peach’s best weapon in the entire game, increasing Peach’s attack by a whopping 90 points, making it a must for the Culex fight.

The Miner’s Store entire inventory includes:

  • Lucky Jewel (100 coins).
  • Mystery Egg (100 coins).
  • Feather (250 coins).
  • Piece of metal (Peach’s Frying Pan) (300 coins).

Get the Two Lazy Shells in Rose Town

The Lazy Shell weapon and Lazy Shell armor are must-haves for the Culex fight. In Rose Town, take the northward passage to reach the gardener Toad’s house. To get the two Lazy Shells, you’ll need to give him a Seed and some Fertilizer.

To get the Seed, you first must defeat Megasmilax in Bean Valley on the way to Nimbus Land. This is a required part of the story, so you can’t miss it. Afterward, Beezo will drop a Seed at the end of the path, which you can pick up before taking the Warp Pipe onward.

After defeating Valentina in the Nimbus Land castle, you can pick up the Fertilizer. Walk against the right edge of Nimbus Land until you find the invisible walkway. Continue down the invisible floor until you find Beezo. Speak to him to get the Fertilizer.

Once you have both the Seed and Fertilizer, take them back to the gardener Toad in Rose Town to grow a beanstalk that leads to the Lazy Shells. The Lazy Shell weapon is Mario’s best weapon in the game, increasing his Attack by 90.

The Lazy Shell armor decreases the wearer’s offenses and Speed by 50 points each but increases both their defensive stats by a massive value of 127. On top of that, the wearer gains invincibility against all status ailments and elemental attacks. Give Peach the Lazy Shell armor to ensure she can tough it out against Culex’s attacks. Peach is your party’s best healer and also has access to a revival skill, so keeping her alive is crucial so she can keep the rest of the party in tip-top shape.

Get the Safety Ring in the Sunken Ship

The Safety Ring (not the Safety Badge) is one of the best accessories in the game, and it can be easy to miss. In the Sunken Ship, you’ll come across a large underwater space with a whole lot of barrels and a group of Bloopers. Behind the barrels is a bit of light peeking out.

It’s not obvious at first glance, but you can actually enter the maze of barrels. Walk until you bump into the wall between the cannon and the barrels, then turn right and keep going—you’ll be behind the barrels and can enter the hidden door.

Open the treasure chest to get the Safety Ring. The Safety Ring makes the wearer immune to instant death attacks and all status ailments, as well as increasing their Defense, Magic Defense, and Speed by 5. Combining the Safety Ring with the Lazy Shell armor makes Peach virtually invincible, which will be crucial in the upcoming Culex fight.

Get the Ghost Medal in Monstro Town

The Ghost Medal is a fantastic accessory that halves the damage the wearer takes (excluding instant death attacks). It’s recommended for less defensive party members such as Geno or Mallow so they can last as long as possible through the Culex fight.

To get the Ghost Medal, you first have to initiate the Three Musty Fears’s flag hunt. In Monstro Town, enter the door to the right of the item shop. If all you see in the room is a bed with a sign on it, you’re in the right place. Interact with the light in the upper right of the room to rest in the bed, and the Three Musty Fears will appear to start the flag hunt. The flags can be found in the following locations:

  • Between the letters “O” and “A” at the end of the racetrack on Yo’ster Isle.
  • On the back of the “Welcome” sign in Rose Town.
  • In the bed in Mario’s home.

Once you’ve found all three flags, return to the Three Musty Fears’s home and sleep in the bed again. The Three Musty Fears will appear and give you the Ghost Medal. It will be equipped on Mario rather than in your inventory, but you’re free to move it to Geno or Mallow. Mario will do better with the Jinx Belt accessory, which you can also pick up while in Monstro Town.

Get the Jinx Belt in Monstro Town

Take the stairs at the east end of Monstro Town up to a door with a sign with the letter “J” on it. Inside is a dojo where you’ll need to defeat Jagger the armored Koopa, and Jinx, the dojo’s sensei. You must defeat Jinx three times, with each battle getting progressively more challenging, to obtain the Jinx Belt.


In the third battle against Jinx, he will use an attack called Silver Bullet that causes instant death. If you have the Safety Ring already, equip it on Peach to keep her safe and always ready to revive her fallen comrades. Her Triple Attack with Mario and Geno grants everyone immunity to the next attack they take, including Silver Bullet. Make use of it to keep everyone alive and hitting back at Jinx.

The Jinx Belt gives its wearer immunity to instant death attacks while also boosting their Attack and Defense by 27 points each, and increasing their Speed by 12. This is a good accessory for Mario, who is always in your party and will be mostly on the offensive.

Start With a 100% Party Gauge

As you complete the above tasks, build up your party gauge by successfully performing timed button presses. Although you’ll want to use Mario, Geno, and Peach’s Triple Move against Jinx to protect the party from his instant death attack, you should battle some extra enemies afterward to build your party gauge back up to 100%. This way, you can start the Culex battle with a powerful Triple Attack.

Culex Battle Guide

Sample Party Builds for the Battle Against Culex

The following table lists sample party builds for battling Culex before defeating the final boss of the game. You’ll gain access to stronger weapons after beating the game, but it’s possible to defeat Culex before that point. Doing so will give you the Quartz Charm to help you against the game’s final boss.

MarioLazy ShellHero ShirtJinx Belt
MallowSonic CymbalsPrince PantsGhost Medal
GenoStar GunStar CapeFeather
BowserDrill ClawHeel ShellBooster’s Charm
PeachFrying PanLazy ShellSafety Ring

There are additional armor and accessories that are worth equipping but are much more challenging to obtain and thus aren’t required. If you can get the Attack Scarf from the Chow in Monstro Town for doing 30 Super Jumps in a row, equip it on Mario and give the Jinx Belt to Geno instead. If you can get the Troopa Medal for scaling the cliff at Land’s End in under 12 seconds, equip it on Bowser to improve his offenses and help mitigate his low Speed.

Culex and the Elemental Crystals: General Strategy

Culex’s first move will be to summon his four elemental crystals. If you’re playing on Breezy difficulty, there’s a chance you’ll outspeed Culex and have a turn without the crystals. If you’re playing on Normal difficulty, the crystals will arrive before you have your first turn.

Use Mario, Geno, and Bowser as your initial party, and use the Shooting Star Shot Triple Attack once all the crystals are on the field. Shooting Star Shot will attack all enemies randomly and also buff your entire party for three turns.

After using Shooting Star Shot, and while the crystals are still on the field, swap Geno for Mallow and Bowser for Peach. The crystals have more physical Defense than Magic Defense, so you’ll want Mario and Mallow to hit the crystals’ elemental weaknesses with their special moves.

Peach will be immune to the crystals’ own elemental attacks, so she can focus on keeping Mario and Mallow’s HP topped off with Therapy and Group Hug, and she can use Come Back to revive anyone when necessary. Keep the party’s FP up with Maple Syrup, and don’t be afraid to use the Pick Me Up item if you’re concerned about missing Come Back’s timed button press. You’ll want your party to have as much HP as possible at all times, so it’s better to be safe than sorry.

Focus on defeating the crystals first. The four of them have powerful party-hitting attacks, making them the worst part of this fight. Culex is no slouch, either, but his attacks are much more manageable when he’s by himself.

Once you’ve destroyed the crystals, swap Mallow for Geno or Bowser. Unlike the crystals, Culex has only marginally more physical Defense than Magic Defense. This, combined with his lack of elemental weaknesses, makes regular attacks more effective on him in the long run. Save your FP for Geno’s non-elemental special moves and for Peach’s healing. Continue to keep the party’s health as high as possible. If you see your FP is running low, have someone besides Peach use Maple Syrup, or save FP by using Mid Mushrooms when someone is missing only 80 HP or less.

Fire Crystal: Stats and Weaknesses

HPAttackMagic AttackSpeedDefenseMagic DefenseWeaknessImmunity
(2250 in Breezy mode)
01301010060IceFire, all status ailments

Mallow’s Snowy special attack won’t damage the Water Crystal, but it will do residual damage onto all of the other crystals and hit the Fire Crystal’s weakness. When you’re focusing on taking out the Fire Crystal with Snowy, use Mario’s Super Fireball special attack on the Water Crystal to make up for the lost damage.

Since Snowy is your only Ice element move, you should target the Fire Crystal after taking down the Wind Crystal. Snowy will chip away at the Earth Crystal’s HP in the meantime, softening it up for later.

Water Crystal: Stats and Weaknesses

HPAttackMagic AttackSpeedDefenseMagic DefenseWeaknessImmunity
(1620 in Breezy mode)
01201213050FireIce, all status ailments

When focusing on the Water Crystal, use Mario’s Super Fireball special move. You’ll concentrate super effective fire damage onto it and save FP compared to Ultra Fireball, which costs a lot more FP and has a chance to hit the Fire Crystal for no damage. It’s advisable to wear the Water Crystal down with Mario while Mallow uses Snowy to deal with the Fire Crystal.

Earth Crystal: Stats and Weaknesses

HPAttackMagic AttackSpeedDefenseMagic DefenseWeaknessImmunity
(2880 in Breezy mode)
08017033ThunderJump, all status ailments

Use Mallow’s Shocker special move to hit the Earth Crystal’s weakness. Thunderbolt may cost a lost less FP, but it does no damage to the Wind Crystal. Don’t worry about getting residual damage onto the other crystals; Snowy will handle that. If you’ve left the Earth Crystal for the end, Shocker deals a lot more damage compared to Thunderbolt, making it worth the extra FP cost.

Wind Crystal: Stats and Weaknesses

HPAttackMagic AttackSpeedDefenseMagic DefenseWeaknessImmunity
(720 in Breezy mode)
0603020088JumpThunder, all status ailments

It’s advisable to focus on taking out the Wind Crystal first because of its super high Speed as well as its low HP compared to the rest of Culex’s crew. Use Super Jump to concentrate super effective Jump damage onto it, since Ultra Jump may land on the Earth Crystal at some point and do no damage at all.

Culex: Stats and Weaknesses

HPAttackMagic AttackSpeedDefenseMagic DefenseWeaknessImmunity
(3686 in Breezy mode)
2501005010080NoneAll status ailments

After taking out the crystals, use regular attacks against Culex so you can save FP for Peach’s healing. If you have FP to spare, use Geno’s special moves against Culex (except for Geno Whirl, which Culex is immune to) since they have no elemental properties. Geno Boost is also helpful to use on Mario to increase his attack; if you time the button press right, Geno Boost will also increase Mario’s defense.

Culex has very strong party-wide and single-target attacks. Be especially careful of Dark Star, a single-target move that can easily take out someone with lower Magic Defense or who isn’t fully healed. Press A right when the star is about to land on you for the third time to mitigate the damage.

Triple Attack Suggestions

After starting with Mario, Geno, and Bowser’s Shooting Star Shot Triple Attack, your party will almost always include Mario and Peach. If Geno or Bowser is down for the count and your party is low on HP, use Mario, Mallow, and Peach’s Healing Rainbow to revive and fully heal everyone.

Mario, Geno, and Peach’s Spare-Us-All is another great defensive Triple Attack choice for when you don’t need to revive anyone outside of your active party.

It will be challenging to get Mario, Geno, and Bowser back together safely to pull off another Shooting Star Shot, but Mario, Bowser, and Peach can use Starry Shell Spike for major damage against all remaining enemies.

Who to Give the Quartz Charm To

Continue healing your team with Peach and piling on the damage with Mario and Geno or Bowser, swapping them out for Mallow if you need to use Healing Rainbow. Eventually you’ll defeat Culex, who will give you the Quartz Charm and disappear.

Because Peach is already invincible with her Lazy Shell and Safety Ring setup, you should give the Quartz Charm to Mario, who can’t leave your party and as such is worth decking out with the best equipment. If you have the Attack Scarf on him, however, Geno is a good alternate choice for the Quartz Charm.

After defeating Culex, his door will disappear from Monstro Town… but this isn’t where Culex’s story ends! Check out our guide to the Super Mario RPG secret and post-game bosses when you’re ready to take on an even greater challenge.

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Niki Fakhoori
Niki’s love for video games encompasses a wide range of genres, but she is especially fond of RPGs, adventure games, visual novels, simulation games, and fighting games. Her favorite video game-related pastime is asking her unwieldy backlog why she doesn’t have any new games to play. When she isn’t playing or writing about video games, she’s playing with cats, journaling, painting, or obsessing over the latest news in the world of stationery and planners.