Book of Inferno Slot Review
Quickspin delivered a visually striking release with Book of Inferno, a demon-hunting adventure set deep in the underworld. This isn’t your typical book slot – the marked symbols mechanic and symbol upgrade features introduce genuine innovation to a familiar game template. With its distinctive dark aesthetic featuring swirling fire, menacing demons, and the heroine Anna on her underworld quest, the game stands apart from the parade of conventional fantasy-themed releases cluttering the market.
Base Game & Features
Book of Inferno runs on a classic 5×3 grid with 10 fixed paylines, using traditional line-based win evaluation. The visual presentation immediately distinguishes the game from competitors – fiery lakes, pentagram symbols, and menacing demon characters create a cohesive dark aesthetic that reinforces the underworld theme. Rather than relying purely on theme for appeal, Quickspin implemented two genuine mechanical innovations that elevate standard book slot gameplay.
Marked Symbols Mechanic
Each spin randomly designates one symbol type as “marked.” When this marked symbol creates a winning combination, it expands to cover the entire reel, substantially increasing win potential. This mechanic randomly targets different symbols across spins, creating unpredictable engagement. The marked symbol selection happens automatically before each spin, so you’ll always know which symbol can expand – though landing it is another matter entirely.
Symbol Upgrade Feature
When the Book symbol lands, triggering free spins, it initiates the Symbol Upgrade mechanic. During bonus rounds, marked symbols don’t just expand – they upgrade to higher-value symbols as the round progresses. This creates a compounding mechanic where persistent marked symbols through the bonus round can transform into premium symbols, generating substantially larger payouts than base game equivalents.
Book of Inferno Free Spins
Landing 3 or more Book symbols (scatters) triggers the free spins feature. The number of spins awarded depends on the trigger tier – 5 Books award 20 free spins with a significant 200x multiplier applied to all wins. These aren’t passive spins; marked symbols remain persistent throughout the bonus round, continuously upgrading as new Books land. This creates genuine potential for substantial wins, particularly when the right symbol types are marked early in the round.
Retriggers are possible during the free spins feature itself. Landing additional Books during bonus rounds extends your run, adding to win potential during the most exciting game phase. The multiplier system – starting at 200x and potentially increasing through symbol progression – rewards patience and bankroll management during what Quickspin designed as a genuine thrill ride mechanic.
Bonus Buy Feature
Players can purchase entry to the free spins feature for 125 times their stake. This guarantees 3 or more Book symbols on the next spin, immediately triggering the bonus round. The Bonus Buy option carries an RTP of 96.65%, higher than the base 96.15%, making it mathematically rewarding for high-volatility chasers willing to skip dry spells. Note: Bonus Buy is not available to UK players due to UKGC regulations on feature purchase mechanics.
Our Honest Verdict
Book of Inferno represents Quickspin’s commitment to elevating the book slot formula through genuine mechanical innovation paired with exceptional visual presentation. The marked symbols system and symbol upgrade mechanic differentiate it meaningfully from the sprawling roster of conventional book releases. These aren’t superficial additions – they fundamentally alter how the base game plays and how bonus rounds develop.
The 4/5 volatility rating (per Quickspin’s official assessment) accurately reflects gameplay reality. Marked symbol activations occur randomly, so base game wins remain infrequent and unpredictable. This volatility will prove punishing for players seeking consistent smaller wins between bonus rounds. For high-variance enthusiasts comfortable with extended dry spells, however, the 5,846x maximum win and symbol upgrade mechanics deliver genuine win potential when bonuses finally land.
The visual presentation deserves particular emphasis. Quickspin demonstrated meticulous attention to the dark demonic aesthetic – swirling fire, pentagram symbols, menacing demon characters, and a grimy soundtrack that complements rather than overshadows gameplay. This coherent visual direction separates the game from competitors trading in generic fantasy artwork. The heroine Anna and her underworld quest add narrative texture absent from many modern slots.
Experienced players seeking complex bonus mechanics might find the overall gameplay simpler than expected – the core loop remains straightforward payline evaluation enhanced by symbol expansion. Players comfortable with traditional book slot rhythms but appreciating mechanical innovation and visual excellence will find substantially more engagement here than genre standards. For casual players uncomfortable with high volatility, however, Book of Inferno demands either patience or frequent bonus buy purchases, limiting its broad appeal.
Book of Inferno delivers a premium high-volatility release built specifically for Quickspin enthusiasts and players who value presentation quality alongside mathematical design. The innovative mechanics justify the inclusion in any portfolio, though the high volatility and dark theme ensure this remains a niche title rather than mass-market offering. Rating: 7.5/10
Book of Inferno FAQs
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What is the RTP of Book of Inferno slot?
The certified RTP of Book of Inferno is 96.15%. Operators can adjust the RTP down to 94.19% or 87.16% depending on market requirements. When using the Bonus Buy feature at 125x stake, the RTP increases to 96.65%, rewarding players who opt for feature purchase. -
What is the maximum win in Book of Inferno?
The maximum win available in Book of Inferno is 5,846x bet. If the sum of a single game round exceeds this amount, the game will end and award 5,846x bet as the final payout. This cap is enforced consistently across all play sessions. -
How volatile is Book of Inferno slot?
Book of Inferno is rated as High volatility by Quickspin (4 out of 5). High volatility means wins may occur less frequently during base gameplay, but they can be significant when they do occur. This rating is accurate to player experience – expect extended dry spells between feature triggers, particularly for marked symbol expansions. -
What are the key features of Book of Inferno?
Book of Inferno features Marked Symbols that expand to cover whole reels when they create wins. A Symbol Upgrade Mechanic upgrades marked symbols to higher value symbols when a Book lands, triggering free spins. Free Spins are triggered by 3+ Book symbols with enhanced multipliers (200x for the most common trigger). Players can buy free spins for 125x their bet with an RTP of 96.65%. Note: Bonus Buy is not available to UK players due to UKGC regulations. -
What is the Bonus Buy cost for Book of Inferno?
The Bonus Buy feature for Book of Inferno costs 125x your stake and guarantees 3+ scatters (Books) on the next spin, triggering the free spins feature with an RTP of 96.65% at the highest tier. Bonus Buy offers a guaranteed entry to the feature when dry spells feel extended. Please note: Bonus Buy is not available to UK players due to UKGC regulations. -
How many reels and paylines does Book of Inferno have?
Book of Inferno has 5 reels, 3 rows, and 10 fixed paylines. The game uses a classic book-style mechanic with expanding marked symbols and symbol upgrades during the bonus round, creating a blend of traditional payline gameplay with modern mechanical innovation. -
What is the theme and design of Book of Inferno?
Book of Inferno has a heavy demonic theme with captivating design elements including swirling lakes of fire, pentagrams, frightening demons, and heroine character Anna on a demon-hunting quest. The game features fiery visuals, intricate symbol design, and a hardcore, grimy soundtrack that complements the dark underworld aesthetic. Quickspin’s visual execution separates this game significantly from competitors. -
Are there RTP variations available for Book of Inferno?
Yes, Book of Inferno offers RTP options between 94.19% and 96.15%, with 96.15% being the standard and highest RTP. Operators can adjust RTPs based on market requirements, with lower options at 94.19% and 87.16%. Check with your operator to confirm which RTP you’re playing at, as regional licensing requirements vary.


