Book of Monsters

Book of Monsters is a cluster slot where Halloween monsters fill a 7×7 grid. The core of the game is the Fat Symbol you pick in free spins, which swells from 1×1 all the way up to 7×7.

Book of Monsters official video

On your first spins

You win by finding a cluster of 5 or more matching symbols, and base game wins come roughly once every 4.31 spins on average. Occasionally a big symbol such as 3×3 or 4×4 drops in whole, and it can reach up to 7×7. In the free slot demo, seeing one big symbol take up half the screen is quite impressive.

How wins happen

On the 7×7 grid, clusters can connect from 5 up to 49 matching symbols. When a big symbol lands, a large area fills with the same picture at once, so clusters grow easily. Volatility is medium and the bet range is 0.2 to 240.

Once you enter the bonus round

4 to 7 bonus symbols start 5 to 8 free spins, and one random symbol is chosen as the Fat Symbol. Before the round begins, you can gamble to increase your free spins up to 8 or switch to a higher-paying Fat Symbol. During free spins, when enough symbols matching the Fat Symbol gather, it grows one size at a time, and each growth adds 1 to 3 spins.

This game by the numbers

Free spins are fairly rare, about once every 440 spins on average. Wins over 1,000x come about once in 50,700 spins, and the 5,000x max win is about a 1 in 220,000 chance. Bonus buy costs 100x your bet, and Ante Bet is a 2x option.

In one line

This Pragmatic Play slot grows clusters with a unique symbol-size mechanic. With the gamble option as well, you get the feel of adjusting the bonus by your own hand.

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