Selected-symbol expansions
A qualifying selected symbol fills all four rows of its reels and pays its matching value on all 20 lines. Each selected symbol is evaluated independently on the original revealed board.
Helio Labs
Book
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A 5 Γ 4 library slot with 20 fixed lines and selected-symbol expansions. Collect Scatter Tomes to unlock bonus spins, add unique symbols through retriggers, and discover the internal Hidden bonus.
View on Stake Official game page Β· Opens on Stake
StudioHelio Labs
StatusLive release
Published RTP96.00%
Layout5 reels Γ 4 rows
Paylines20 fixed
Maximum win20,000Γ base play
THE GAME, EXPLAINED
How Book plays
Ordinary line wins use three, four or five matching symbols on adjacent reels from the left. Book has no Wilds. During a bonus, selected symbols can expand when they appear on at least three distinct reels, even when those reels are separated.
Game features
4 key mechanicsRegular, Super & Epic
Three, four or five ordinary Scatter Tomes trigger Regular, Super or Epic. They start with 8, 10 or 12 spins and 1, 2 or 3 selected symbols respectively.
Retriggers
An eligible three-Scatter retrigger adds the tierβs starting spin count and one new unique selected symbol. Both spin and symbol retriggers stop once seven symbols are selected.
Mystery & Hidden
Mystery selects no bonus, Super, Epic or Hidden. Hidden also has a valid four-Scatter-plus-Hidden-Tome trigger and begins with 15 spins and five selected symbols. It has no standalone purchase mode.
Play modes
8 selectable modesPlay multipliers apply to the selected base amount. Symbol values and round maximums use the base amount.
| Mode | Play multiplier | What changes |
|---|---|---|
| Base | 1Γ | An ordinary spin with natural Regular, Super, Epic or Hidden bonus triggers. |
| Enhancer | 3Γ | An ordinary spin with a greater overall bonus chance than Base. Regular, Super, Epic and Hidden can trigger. |
| Super Enhancer | 10Γ | An ordinary spin with increased bonus chance. Only Super, Epic or Hidden can trigger; never Regular. A third ordinary SC guarantees at least one more ordinary SC by the final result. |
| Feature Spin | 75Γ | One premium symbol is selected for one spin. That same premium is guaranteed on at least 3 distinct reels, possibly 4 or 5. Its expansion gives the matching paytable value on all 20 lines. Ordinary wins are counted first. No additional Scatter bonus. |
| Regular | 100Γ | Starts 8 bonus spins with 1 selected symbol. Each eligible retrigger adds 8 spins and 1 new unique symbol, until 7 are selected. |
| Super | 250Γ | Starts 10 bonus spins with 2 selected symbols. Each eligible retrigger adds 10 spins and 1 new unique symbol, until 7 are selected. |
| Epic | 500Γ | Starts 12 bonus spins with 3 selected symbols. Each eligible retrigger adds 12 spins and 1 new unique symbol, until 7 are selected. |
| Mystery | 250Γ | Each play selects: 65% no bonus and zero win; 25% Super; 5% Epic; 5% Hidden. There is no Regular branch. The mode stays selected until changed. |
Symbol paytable
Values are per ordinary winning line, as multiples of the base play. A selected-symbol expansion applies its qualifying value across all 20 lines. Scatter Tome and Hidden Tome are trigger-only.
| Symbol | 3 matching | 4 matching | 5 matching |
|---|---|---|---|
| 10 | 0.1Γ | 0.5Γ | 2Γ |
| J | 0.2Γ | 0.8Γ | 3Γ |
| Q | 0.2Γ | 1Γ | 5Γ |
| K | 0.3Γ | 1.5Γ | 7.5Γ |
| A | 0.5Γ | 2.5Γ | 10Γ |
| Quill | 1Γ | 5Γ | 25Γ |
| Wax Seal | 1.5Γ | 7.5Γ | 50Γ |
| Archive Key | 2Γ | 12.5Γ | 100Γ |
| Astrolabe | 3Γ | 20Γ | 250Γ |
| Illuminated Codex | 5Γ | 50Γ | 1,000Γ |
Published RTP comes from the official game listing. Actual results vary.
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