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Super Mario RPG: How to Unlock and Beat the Culex Secret Boss Encounter

Face your toughest challenge yet in Super Mario RPG. Here's how to beat Culex.

There are battles that are difficult, and there are those that truly test your mettle. Indeed, this was one of the hardest for me in the game, and if you’re here, you’re struggling, too. Here, I’ll discuss how to unlock and beat the Culex secret boss in Super Mario RPG.

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How to Unlock and Beat Culex in Super Mario RPG

To unlock the Culex secret boss in Super Mario RPG, you need to gain access to the ornate door in Monstro Town. Once you do, be ready for one of the toughest encounters in the game.

How to Unlock the Monstro Town Door

Though it’s a secret, unlocking the Monstro Town Door is quite simple. Here’s what you need to do:

  • Go to Moleville and enter the house directly north of the shop.
  • Talk to the NPC in the corner and buy the Fireworks for 500 gold.
  • Exit the house and talk to a child behind some wooden crates. Exchange the Fireworks for the Shiny Stone.
  • Make your way to Monstro Town and interact with the ornate door. Having the Shiny Stone will open the room.

Culex Secret Boss Abilities

What makes the Culex unique in Super Mario RPG is that this secret boss has its old 16-bit sprites, reminiscent of how it was in the original game. The encounter is also very difficult since your opponent is surrounded by four crystal minions. These represent different elements, and they all cast their own spells, including debilitating status effects.

I suggest obtaining and equipping the Ghost Medal and Super Suit to buff your characters before the bout. Your healer (i.e., Peach) should also have the Trueform Pin so she doesn’t get transformed.

In any case, here are the attacks that you need to watch out for:

  • Single-target abilities: Diamond Saw, Hot Shot, Flame, Blast, and Dark Star — These can be blocked. However, due to different animations, it’s hard to always keep your combo counter up.
  • Multi-target abilities: Petal Blast, Water Blast, Flare, Shredder, Light Bubble, and Sand Storm — These attacks can’t be blocked, and they’ll damage or debuff all party members.
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Best Party Composition for the Culex Secret Boss Encounter

Early in the secret boss fight against Culex, you’ll have to contend with up to five attacks from different targets. As such, you need to deal area-of-effect (AoE) damage that hits all hostiles, while also having a means of healing the entire party.

In my case, I personally had a team that consisted of Mario, Geno, and Peach:

  • Peach was naturally the healer. I had her use Group Hug whenever the party took a lot of hits.
  • Geno was the AoE damage dealer. I had him cast Geno Blast and Geno Flash when possible.
  • Mario only did normal attacks, or he’d pop Maple Syrup to restore the group’s flower points (FP).
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I continued whittling down all the targets. As more and more crystals were destroyed, the fight became progressively easier. Eventually, with Culex vanquished, I received the Quartz Charm. Funny enough, Culex does mention that it’s jealous of the 3D world, and you might see it once more.

That’s how to beat Culex in Super Mario RPG. You might be curious as to whether or not you’ll meet this foe once more, perhaps as part of post-game content. For more tips and strategies, you can check out our SMRPG guides hub.

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Jason Rodriguez
Jason Rodriguez is a game reviewer and guides writer from the Philippines. With around 5,000 published articles, he's freelanced for numerous outlets, including GameSkinny, GameSpot, Polygon, IGN, PCGamesN, PC Invasion, and more.