Special Symbol
Area Symbol Transformation
A feature where a random symbol on the grid is selected as a "Marked Target," and all symbols within a 3x3 or 5x5 area surrounding it transform to match that target symbol.
Special Expanding Symbol
A popular feature that expands in a unique way
The Special Expanding Symbol is one of the most iconic and popular mechanisms in online slot history, a core free spins feature primarily found in 'Book of...' series games.
The essence of this feature is that one regular symbol, randomly selected at the start of the free spins, gains a special power. This symbol, as long as it appears on the reels in the required number to form a win, will expand to cover its entire reel and create massive wins regardless of its position.
More Features in This Family
Special Symbol
Bonus Overlay Symbol
A feature where a special effect is overlaid on a regular symbol, which then awards a special bonus (e.g., free spins).
Special Symbol
Cash Symbol Cloning
A feature where existing cash symbols clone their values onto adjacent empty positions, multiplying the total collectable prizes.
Special Symbol
Cluster Merge & Level Up
A dynamic mechanic where winning clusters merge and transform into higher-level symbols, driving continuous progression.
All Slots with This Feature
300SPINS™
hardcore
Book of Claws: Lock&Choose is a ancient Egyptian adventure-themed slot by Clawbuster. The slot is built on a 5x3 reel grid with 10 paylines and offers a theoretical maximum win of x5,000. It also comes with special features such as Special Expanding Symbol and Ante Bet, adding extra gameplay variety from the feature mix and more control over bonus frequency and stake risk.
Preview
Sushi Slice is a sushi-themed slot by Happy Duck. The slot is built on a 5x5 reel grid with 3,125 ways and offers a theoretical maximum win of x10,000. It also comes with special features such as Special Expanding Symbol and Symbol Split, adding extra gameplay variety from the feature mix and symbol transformations that change the round shape.
Preview
Voltage Blitz Rapid Boost is a cosmic-themed slot by Koala Games. The slot is built around changeable reels. It also comes with special features such as Hold and Respin and Fixed Jackpot, adding locked-symbol bonus tension and extra jackpot targets alongside regular wins.
Featured
City of Sin is a noir crime jazz bar slot by Degen Studios. The slot is built on a 5x3 reel grid with 20 paylines and offers a theoretical maximum win of x15,000. It also comes with special features such as Global Multiplier and Special Expanding Symbol, adding multiplier-driven win scaling and extra gameplay variety from the feature mix.
Preview
Gift of Midas is a Greek mythology-themed slot by Endorphina. The slot is built on a 5x3 reel grid with 10 paylines and offers a theoretical maximum win of x6,500. It also comes with special features such as Special Expanding Symbol and Collection Meter, adding extra gameplay variety from the feature mix and collection-based value building.
300SPINS™
balance
Book of Khonsu is an Egyptian-themed slot by GameBeat. The slot is built on a 5x3 reel grid with 10 paylines and offers a theoretical maximum win of x5,000. It also comes with special features such as Fixed Jackpot and Multi-Function Symbol, adding extra jackpot targets alongside regular wins and symbol transformations that change the round shape.
Preview
Dragonspire is a dragon-themed fantasy slot by Paperclip Gaming. The slot is built on a 5x5 reel grid with cluster pays and offers a theoretical maximum win of x10,000. It also comes with special features such as Cascading Reels and Cluster Pays, adding repeat-win chances from cascading symbol drops and cluster-based hit patterns beyond fixed lines.
Preview
Book of the Cleo is a Ancient Egyptian, Cleopatra-themed slot by Zillion Games. The slot is built on a 5x3 reel grid with 25 paylines and offers a theoretical maximum win of x2,000. It also comes with special features such as Hold and Respin and Fixed Jackpot, adding locked-symbol bonus tension and extra jackpot targets alongside regular wins.
The information provided by SlotWise, including reviews, guides, and analysis, is for informational and entertainment purposes only.
All data is based on our own 300-spin tests and is not a guarantee of future results.
Please gamble responsibly and within your means.
This site is intended for users aged 19 and over.
ⓒ SlotWise, 2025, All rights reserved
Comments
No comments yet. Be the first to comment!