Book of Monsters: Slot Overview
At first glance, Book of Monsters might sound like a Hogwarts-required reading assignment, but in reality, Pragmatic Play has crafted a cluster-paying grid slot that plays by different rules than the traditional ‘Book of’ format. While books do appear and flip open to reveal free spins and randomly chosen symbols, the game doesn’t follow the usual ‘Book of’ mechanics, where special symbols expand across their reels. Instead, the expanding mechanic in the bonus round functions more like Fat Rabbit than Book of Dead, giving the gameplay a fresh twist.
Despite the monster theme, the creatures in Book of Monsters aren’t exactly nightmare fuel. Their wide eyes and toothy grins give off a Reactoonz-style charm, making them seem more mischievous than menacing. However, their cave dwelling is a bit more ominous, filled with glowing-eyed spectres lurking in the shadows. The atmosphere shifts when free spins trigger, with the blue-lit cave turning into an intense orange glow—a sight players will want to see often, as Book of Monsters’ real action is most likely to unfold in the bonus round.
Book of Monsters is played on a 7×7 grid, utilizing a cluster pays system, where winning combinations form when at least 5 matching symbols connect vertically and/or horizontally. The base game is relatively straightforward, with no additional features, but players can opt to buy into the bonus round or activate the Ante Bet, which increases the chance of triggering free spins by 7x—though it doubles the stake when active.
Players can place base bets ranging from $0.20 to $/€240 per spin, and regardless of the bet configuration, the game remains highly volatile, with a maximum RTP of 96.5%.
Symbols & Payouts
The low-paying symbols feature both a card rank and a suit, including:
- Jack of Diamonds
- Queen of Clubs
- King of Hearts
- Ace of Spades
The premium symbols are three colorful monsters:
- Purple Monster
- Green Monster
- Red Monster
Cluster payouts vary based on the number of matching symbols:
- 5-symbol clusters pay 0.2x to 2x the bet.
- The highest-paying cluster (49-symbols) awards 100x to 5,000x the bet.
Fat Symbols Mechanic
While there are no wild symbols, randomly triggered Fat Symbols can appear in the base game, taking up sizes of 3×3, 4×4, 5×5, 6×6, or even 7×7, potentially leading to massive cluster wins.
With its simple yet volatile gameplay, high max win potential, and cluster mechanics, Book of Monsters offers a mix of unpredictability and thrill, especially when those Fat Symbols hit the grid.
Book of Monsters: Free Spins & Bonus Features
Triggering Free Spins
- Landing 4, 5, 6, or 7 scatters in the base game awards 5, 6, 7, or 8 free spins, respectively.
- If the Ante Bet is activated, 3, 4, 5, 6, or 7 scatters will instead grant 4, 5, 6, 7, or 8 free spins, respectively.
Choosing the Fat Symbol & Gamble Feature
- Before free spins begin, a random pay symbol is chosen as the Fat Symbol for the bonus round.
- Players have the option to gamble for:
- A more valuable Fat Symbol.
- Additional free spins.
- Or they can collect and start the round immediately.
- If the gamble fails and the book reveals “The End,” the bonus round is lost.
- If successful, players can win up to 8 extra free spins or upgrade to the highest-value Fat Symbol.
Fat Symbol Progression in Free Spins
- The Fat Symbol starts as a 1×1 symbol, appearing on the grid and moving to a new position on every spin.
- Any matching symbols that land on the grid (and are not overlapped by the Fat Symbol) are collected in a progression meter.
- As players collect symbols, the Fat Symbol increases in size:
| Collected Symbols | Fat Symbol Size |
|---|---|
| 30 symbols | 2×2 |
| +27 more | 3×3 |
| +24 more | 4×4 |
| +20 more | 5×5 |
| +16 more | 6×6 |
| +12 more | 7×7 |
- Each time the Fat Symbol levels up, players receive 1 to 3 additional free spins.
Bonus Buy Option
- Players can purchase the free spins feature directly for 100x the bet.
- When bought, 4, 5, 6, or 7 scatters randomly land, triggering the bonus round.
With its progressive Fat Symbol mechanic, gamble feature, and high volatility, Book of Monsters offers an engaging free spins round where wins can escalate quickly if players build their symbol collection.
Book of Monsters: Slot Verdict
At first glance, Book of Monsters might seem like yet another ‘Book of’ slot, primed to deliver expanding special symbols à la Book of Dead. However, as the saying goes, you shouldn’t judge a book by its cover, and that rings especially true here. Rather than following the traditional ‘Book of’ formula, Book of Monsters carves its own path—though it still borrows familiar elements from past games.
One of the most recognizable elements is the book itself, which is used to trigger free spins and select a random special symbol. Starting with only 5 free spins doesn’t feel particularly generous, making the gamble feature an appealing option. In testing, 5 spins were sometimes enough to level up the Fat Symbol, though not all the way—so, naturally, more free spins mean a better shot at progression.
Another decision players may wrestle with is whether to gamble for a more valuable Fat Symbol. While high-paying symbols bring bigger wins, low-paying symbols appear more frequently, technically making the Fat Symbol easier to level up. This presents an interesting risk-reward choice for players looking to optimize their free spins round.
That said, Book of Monsters lacks a multiplier feature like Royal Potato or a growing wild like Fat Rabbit, meaning its win-building mechanics feel more restricted. However, it does offer a max win of 5,000x, which is achieved by landing a fully expanded 7×7 version of the highest-paying symbol. With a 1 in 547,945 chance of hitting max win, it’s not entirely shocking, but still a rare event.
Ultimately, Book of Monsters is a quirky, unconventional slot that pieces together elements from various inspirations. The base game can feel slow, but the wandering, growing Fat Symbol mechanic adds enough intrigue to make it worth a spin for players who enjoy progression-based gameplay.