Slot review and guide

Book of Monsters at Mrjones Casino: what the paytable and bonus round deliver

Pragmatic Play's horror-themed cluster pays slot with free spins and growing symbols, 96.50% RTP, high volatility where wins come bigger but less often.

Claim Bonus 18+ only. Licensed and regulated by the Anjouan Offshore Finance Authority (ALSI-566940).

Book of Monsters: high volatility cluster pays on a 7x7 grid

Book of Monsters uses cluster pays. Book of Monsters is a high volatility horror slot from Pragmatic Play built on a 7x7 grid where wins form when five or more matching symbols connect horizontally or vertically. The game's defining feature is the FAT symbol, a growing block that can expand from 3x3 to 7x7 and land randomly during base game spins, creating larger winning clusters. Monsters and card ranks pay across the grid; wins clear symbols to let new ones fall into place. Released in March 2025, the game combines cluster mechanics with the monster theme to shape each round around symbol collection and cluster growth.

Is this slot right for your play? Book of Monsters suits you if you enjoy high volatility play where wins arrive less often but can be significantly larger, and if you're comfortable with the game's horror setting and monster imagery. You'll need patience between wins and a bankroll sized for longer dry spells. The slot's range of bet sizes—from A$0.20 to A$480—works for many players, though the ante bet option doubles your stake at A$10 per spin when activated. If you prefer frequent small wins or find monster themes unsettling, this game's structure may not match your play style.

Free Spins: where the game changes shape. Free Spins reshape your round and hold the game's biggest payouts. Triggering requires four or more Bonus symbols in the base game, or three when you activate the ante bet. When free spins begin, you select a FAT symbol tier and watch it grow as matching symbols land during the round. Each time your chosen FAT symbol fills its collection meter, it expands and awards bonus spins. A gamble screen before spins start lets you upgrade your symbol tier, increase spin count, or confirm and play. This built-in choice within the bonus round means every free spin session can unfold differently.

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Key game figures

The core figures of this game

You'll understand what each figure means when you start playing.

Pragmatic Play

MakerPragmatic Play

Return to player96.50%

VolatilityHigh

Maximum win multiplex5 000

A$2 400 000

Top win at maximum stakeA$2 400 000

Released27/03/2025

5 steps to spin

How does a round of Book of Monsters work?

At Mrjones Casino, you control your stake before each spin and can set limits before you start.

What bet range does this slot offer?

You choose your bet amount from A$0.20 up to A$480. If you select Ante Bet, your bet doubles to A$10 for example stakes, which increases your chances of triggering Free Spins but also raises your cost per spin.

Clusters of touching symbols

On the 7x7 grid, you need at least 5 matching symbols touching horizontally or vertically to form a winning cluster. When they connect, those symbols disappear and new ones drop down to fill the spaces.

Book of Monsters' FAT symbol feature

During any spin, a FAT symbol can appear randomly as a large block (from 3x3 up to 7x7) covering multiple positions at once. This giant symbol acts as a wild, helping you form bigger clusters or combinations you might not otherwise hit.

From trigger to bonus round

Free Spins start when you land 4 or more Bonus symbols on a single spin, or 3 or more if you have Ante Bet active. You are awarded 5 to 8 spins and enter a screen where you can upgrade your FAT symbol or spin count before the round begins.

Set your spending boundary

Before you start playing, you can set session time reminders, loss limits or deposit limits through Mrjones Casino. These boundaries help you play within your comfort zone and stop automatically if you reach your preset limit.

4 game screens

Book of Monsters: base game and bonus screens

Bonus trigger screen with Bonus symbols highlighted

Gamble choice before Free Spins begins

7x7 grid with cluster of matching monsters

Win animation showing connected symbol payout

FAT symbol growing larger during Free Spins

Final win total at end of Free Spins round

Payout guide

Check what the monsters are worth

Payouts shown are in Australian dollars at a A$0.40 bet. More symbols in your cluster mean higher winnings.

Highest paying

Red Monster5+ A$0.40 · 49+ A$1 000

Green Monster5+ A$0.20 · 49+ A$100

Purple Monster5+ A$0.10 · 49+ A$50

Card values

Ace5+ A$0.08 · 49+ A$40

King5+ A$0.06 · 49+ A$30

Queen5+ A$0.05 · 49+ A$25

Before free spins start, then growing symbols during

Collecting symbols to grow your multiplier. You trigger Free Spins when 4 or more Bonus symbols land, or buy them for 100 times your bet. You receive 5 to 8 spins. A FAT symbol you select starts at 1x1 and grows to 7x7 as matching symbols collect during the round. Each size increase awards 1 to 3 extra spins.

Double your bet to trigger sooner. Enable Ante Bet to multiply your stake by 2.0 and reduce the number of Bonus symbols needed to trigger free spins from 4 down to 3. This mode makes the bonus round more frequent. You cannot buy free spins while Ante Bet is active.

Before the bonus: cluster formation. On the 7x7 grid, you need at least 5 matching symbols in a cluster (touching horizontally or vertically) to form a winning group. During any base game spin, a FAT symbol may appear randomly as a block ranging from 3x3 up to 7x7 tiles.

Know the honest gaps in advance

Book of Monsters bonus timing is random. The bonus round arrives by chance. No player can predict when the next Free Spins will trigger, no matter how many spins they play or which bet they choose.

Will I win in my next session? One session's result is chance. The RTP describes long-term patterns across thousands of spins, not what will happen in your next hour or your next bet.

Book of Monsters maximum win is a rare ceiling. The maximum win of A$2 400 000 is a ceiling that very rarely occurs. Most sessions will not reach it, and most wins will be far smaller.

Book of Monsters RTP explained

Book of Monsters: the house edge and your returns

RTP is the average amount a slot returns to players over many thousands of spins. Each RTP figure shown here applies only to the specific game mode or feature listed next to it; they are not choices the casino makes, but outcomes tied to how you choose to play.

RTP 96.50% · Standard game, Ante Bet, and Buy Free Spins

Average payout per A$100A$96.50

Casino keepsA$3.50

Test drive this slot

From free play to live stakes at Mrjones Casino

You've found Book of Monsters and want to see how it plays without risking your bankroll.

No stakes, no winnings

You spin the grid without spending anything, see how cluster wins form on the 7x7 board, and watch the FAT symbols appear. Your virtual balance never decreases and you earn nothing, so you get a true picture of the game's pace and bonus trigger frequency.

Play demo

Real money stakes and real payouts

You set a real bet amount between A$0.20 and A$480 per spin, and winnings go straight to your account. Each spin costs your chosen stake; bonus rounds come as they do in demo, but now the prizes are yours to keep or spend again.

Play for real money

Book of Monsters is just the start

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In the feature menu

Bonus buy and ante bet options

18+Choose to buy free spins directly or activate an ante bet to make bonus rounds arrive more often.

A$500 (x100)

Jump to the bonus round

Skip the wait for bonus symbols and go straight to free spins. Costs A$500 at your example top bet, unlocking 5 to 8 spins and the growing FAT symbol feature immediately.

A$5 → A$10

What does Ante Bet do?

Double your stake to A$10 and trigger free spins more often. Reduces the BONUS symbols you need from four down to three, giving you roughly seven times more chances to land the bonus.

5 questions answered

Understand Book of Monsters before playing

You've found the slot and want to know what matters before your first bet.

Can I buy Free Spins in Book of Monsters?+

Yes. You can buy Free Spins directly for 100 times your bet. At an A$5 bet, this costs A$500. While Ante Bet is active, the buy option becomes unavailable, so you'll need to turn off Ante Bet first if you want to use it.

Why should I try Book of Monsters in demo mode?+

Demo play lets you see how the 7x7 grid works, watch the FAT symbol grow during Free Spins, and understand the cluster pays system without spending money. You'll recognise the bonus screen and gamble choice when you play for real.

Can I expect frequent wins in Book of Monsters?+

Book of Monsters is high volatility, which means wins come less often and can be much bigger. You might spin several times without a win, but when one lands, the payout can be substantial. This suits players who prefer larger, less frequent payouts.

What happens to the RTP when I use Ante Bet or buy the bonus?+

The standard game runs at 96.50% RTP. This same rate applies whether you activate Ante Bet (the 2x bet multiplier) or buy Free Spins. Your RTP doesn't change based on which option you choose.

Where can I find the bet range in Book of Monsters?+

You can bet from A$0.20 to A$480 per spin. Common bets sit at A$0.40, A$0.50, and A$5. You adjust your stake before each spin to match your session plan.

Your gaming choices matter most

Book of Monsters budget plan. Decide what you can afford to spend on this session and stick to that amount. Your budget should only include money you don't need for everyday living.

Stop before the game stops you. Plan when you'll stop playing before you start, then honour that decision even after a win. Stopping while ahead keeps the fun intact.

Take charge with account limits. Your Mrjones Casino account includes deposit limits and loss limits you can set at any moment. Using them makes your spending predictable.

Book of Monsters isn't everything. If Book of Monsters or any game stops being enjoyable, pause your play or use self-exclusion through your account. Support is available through Gambling Help Online, Lifeline Australia and BetStop.