If you’re a completionist, a masochist, or someone who simply thrives on chaos, then you’ve likely heard of Inscryption‘s most brutal Steam achievement: Skull Storm. This achievement pushes Casey’s Mod to its absolute limit, stacking every single challenge modifier into one unrelenting, punishing run. Only around 2% of players have managed to pull it off—and for good reason. This is the pinnacle of difficulty in Inscryption, and it takes a smart strategy, deep understanding of mechanics, a healthy dose of patience, and yes, a little bit of luck.

This guide walks you through not only how to approach Skull Storm but also reflects on a player’s firsthand experience grinding their way to victory, culminating in one of the most broken builds you could ever imagine.

What is Skull Storm?

Skull Storm is the ultimate challenge in Casey’s Mod, unlocked after beating the base game. It’s a full run against Leshy with every single challenge enabled:

• One life (no room for error)
• Only two items allowed
• No rare cards from bosses
• Start each battle with damage against your scale
• All regular battles become totem fights
• The wall of Grizzlies appears, one of the game’s most difficult combat phases

Even a single one of these modifiers makes the game tougher. Together? They create a gauntlet that demands flawless strategy and a dash of controlled madness.

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Picking the Right Starter Deck

While Skull Storm can be beaten with any of the eight starter decks (as proven by pro player and YouTuber EXO), the most optimal choice—especially for newcomers to the challenge—is the Black Goat Deck. It includes:

• Black Goat
• Mole
• Moose Buck

What makes this deck so powerful is how it plays into the Fair Hand mechanic.

The Fair Hand Mechanic

This mechanic guarantees that your opening hand will always contain a card you can play on your first turn. If your deck has only one one-blood-cost card, and the rest are higher cost, the game will make sure that card is always dealt to you.

So, if you remove the Mole from your deck—by sacrificing it at a campfire, giving it to the Bone Lord, or through other events—you’re left with only one one-cost card: Black Goat. That means every fight starts with a squirrel and a Black Goat, giving you immediate access to three-blood-cost power cards.

This consistency is invaluable in Skull Storm. But you’ll want to avoid picking up any more one-cost or no-cost cards (like Tadpole or Lammergeier), since they can mess with this mechanic. Rare cards like Geck and Ouroboros can’t appear anyway due to the “No Rares” challenge.

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Building Toward Your Win Condition

To survive the wall of Grizzlies and the punishing totem fights, you need a win condition card—something that can deal five or more damage in a single turn. This keeps the scale tipped in your favor, especially during the Bear wave, where a single turn out of balance could cost you the entire run.

Here are several strategies to achieve that:

1. Campfire Buffing – Buff a heavy-hitter like Moose Buck, Grizzly, or Great White at multiple campfires.
2. Create a Touch of Death Attacker – Combine the Touch of Death sigil from an Adder with a card that has Bifurcated Strike (like Pronghorn or Mantis) to eliminate Bears efficiently.
3. Key Items – Use scissors, the skinning knife, the hourglass, or the magical bleach to eliminate or bypass key threats. Even the Harpy’s Bird Leg Fan can let you sneak in a flying hit to finish Leshy.

The key is flexibility. Stack multiple approaches when possible. One method may not be enough.

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Priority Cards to Watch For

In Skull Storm, you don’t want a bloated deck. Smaller, curated decks are more consistent and give you better draws. Here are some standout picks:

• Adder – For its deadly sigil.
• Pronghorn / Mantis – Useful for combining with Touch of Death.
• Great White / Grizzly / Dire Wolf – Big bodies that can become your main damage dealers.
• Cockroach – Its Unkillable sigil is game-changing, especially if transferred to a Black Goat.
• Lammer – Easily a win condition due to its scalable attack based on bones and its innate ability to fly.

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Infinite Engine Combo: Unkillable Goat + Unkillable Lammer

In one incredibly lucky Skull Storm run, the player managed to fuse Unkillable onto both Black Goat and Lammer. This setup, enhanced later by the Fecundity Bird Totem, broke the game.

By playing the Goat, sacrificing it for Lammer, and then sacrificing Lammer to bring Goat back—you create an infinite sacrifice loop that also generates infinite bone tokens. Since Lammer’s attack is based on bones, you can scale him to 20+ attack before ever ringing the bell.

And because both cards are Unkillable, this loop can be repeated every single fight. Add the Fecundity Totem to the mix, and suddenly, Lammer clones itself on every play. What starts as strategy quickly becomes devastation.

Needless to say, the final boss was annihilated in a single turn with four Lammers dealing 20 damage each.

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Dealing with RNG and Planning Ahead

No matter how good your strategy is, RNG still matters in Skull Storm:

• Campfire locations
• Item spawns
• Card choices
• Totem options
• Map layouts

All of these are randomized. Sometimes, things just won’t go your way. It might take 10, 20, or more tries. But each run helps you understand the game better, improving your odds in the next.

When RNG is on your side, capitalize on it. But when it’s not—don’t force it. Restart, reset, and keep learning.

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The Most Important Tip: Pay Attention

This might seem like the simplest advice, but it’s also the most overlooked: pay attention.

Leshy gives you vital clues with his future play indicators. Don’t ignore them. Misreading a sigil or overlooking a combo can be fatal—especially with only one life.

Be deliberate. Analyze the board. Don’t rush into hitting the bell without understanding how the next turn will unfold.

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Final Thoughts

Beating Skull Storm isn’t just about brute force—it’s about deck control, sigil synergy, clever sacrifices, and yes, a touch of madness. Whether you’re chasing bragging rights, that final elusive achievement, or just want to break the game in the most satisfying way possible, Skull Storm is your crucible.

Keep at it. Keep learning. And if you ever pull off that unkillable Lammer combo—just know that Leshy never stood a chance.