Last updated: May 2026. Free-spin behaviour analysed across 300+ test bonus rounds at the four featured AU casinos during April-May 2026.
The free-spins round is where Book of 99 actually pays. Hit frequency in the base game is deliberately low (~23%) and individual base-game payouts are modest — Relax Gaming pulled value out of the base game and put it into the bonus round. Every meaningful Book of 99 session you'll ever have is decided inside one of these 10-spin sequences. This article covers exactly what happens when free spins trigger, how often they trigger, what to expect in terms of payouts, and the retrigger mechanic that can extend the round into the four-figure-multiplier zone.
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How free spins trigger
The trigger: three or more golden book symbols anywhere on the reels in a single spin.
- 3 books = 10 free spins.
- 4 books = 10 free spins + small scatter pay (~20× stake).
- 5 books = 10 free spins + large scatter pay (~200× stake).
The book is both scatter (triggers free spins) and wild (substitutes for any other symbol on a payline). When 3+ books land and trigger the bonus, you also collect the scatter payout shown above. So a 5-book trigger lands you free spins and an immediate A$200 (from a A$1 stake) before the round even starts.
Average trigger frequency: roughly 1 in 220 spins. That's based on observed rates across our test sessions. The studio doesn't publish exact figures.
What happens at the trigger
Sequence when free spins fire:
- Trigger animation. Books glow gold, the screen briefly freezes, dramatic music plays.
- Scatter pay credit. The flat scatter payout (3, 4, or 5 books) is added to your balance.
- The book opens. A large golden book appears centre-screen and the pages flip.
- The expanding symbol is revealed. The pages stop on one randomly selected symbol — your expander for the round.
- The 10 free spins begin.
The expander selection is automatic — you have no input. It's chosen from the 9 paytable symbols (excluding the book itself) with approximately equal probability. The expanding-symbol mechanic is the single most consequential moment in any session.
How each free spin pays
Each of the 10 spins plays out like a normal spin except:
- The chosen expanding symbol, when it lands, expands to fill the entire reel (all 3 rows).
- The expanded symbol pays on every payline that touches the expanded reel, regardless of left-to-right adjacency.
- All other symbols pay normally (left-to-right adjacent paylines).
- The book scatter/wild still acts as wild and can trigger retriggers.
The mechanic effectively gives you a "second math" during the bonus: standard payouts plus the expanding-symbol bonus on top.
Retriggers — the path to extended rounds
During the 10 free spins, landing 3+ books again triggers a retrigger:
- +10 additional free spins added to the round.
- The expanding symbol stays the same across the retrigger.
- Retriggers can chain — a single bonus can theoretically retrigger multiple times (rare; we've documented up to 3 retriggers in a single round).
Retrigger probability: approximately 20-25% of bonus rounds get at least one retrigger. Roughly 5% get two retriggers. Higher numbers are statistically possible but extremely rare.
A retriggered round with Orpheus as the expanding symbol is one of the most consistent paths to a 1,000×+ stake outcome.
Realistic payout distribution
Of every 100 bonus rounds you trigger, expect roughly this distribution of total round payouts:
| Total round win | Frequency | Round context |
|---|---|---|
| 0× – 5× stake | 35% | Card-rank expander, no retrigger, minimal landings |
| 5× – 20× stake | 25% | Card-rank expander, some landings |
| 20× – 50× stake | 15% | Mid-pay expander, moderate landings |
| 50× – 200× stake | 12% | Mid-pay expander with retrigger OR Orpheus expanding once |
| 200× – 500× stake | 7% | Orpheus expanding on 2-3 reels in a single spin |
| 500× – 2,000× stake | 4% | Orpheus expanding multiple times, often with retrigger |
| 2,000× – 12,075× stake | 2% | Orpheus expanding on 4-5 reels across multiple spins |
Roughly 60% of bonus rounds pay below 20× stake. That's the variance. The 99% RTP is delivered by the rare 200×+ rounds carrying enough weight to bring the long-run average up.
What 10 free spins look like in practice — three scenarios
Scenario A: Card-rank expander (the disappointment)
You triggered with 3 books. The pages flip. The expander is the Jack.
Spins 1-3: standard small wins, ~2× stake total.
Spin 4: Jack lands on reel 2. Expansion fires. Pays 0.5× stake.
Spin 5: nothing.
Spin 6: Jack on reels 1 and 3. Double expansion. ~3× stake.
Spins 7-10: minor wins, one more Jack landing.
Total round: ~8× stake. From a A$1 stake, A$8 — below the natural trigger cost. Welcome to high variance.
Scenario B: Snake expander (the solid round)
You triggered with 3 books. The expander is the snake (mid-pay).
Spins 1-2: small payouts.
Spin 3: snake on reels 1 and 2. Expansion. ~8× stake.
Spin 4: snake on reels 1, 3, 5. Triple expansion. ~25× stake.
Spins 5-6: minor wins.
Spin 7: 3 books! Retrigger — +10 spins added.
Spins 8-10: snake on multiple reels, ~30× cumulative.
Spins 11-20 (retrigger): more snake landings, ~50× cumulative.
Total round: ~125× stake. From a A$1 stake, A$125. A good night's win.
Scenario C: Orpheus expander (the dream)
You triggered with 4 books (10 free spins + 20× scatter pay).
Spin 1: Orpheus on reel 3. Single expansion. ~25× stake.
Spin 2: nothing.
Spin 3: Orpheus on reels 1, 2, 4. Triple expansion. ~150× stake.
Spin 4: 3 books! Retrigger.
Spin 5: Orpheus on all 5 reels. 5-of-a-kind expansion. ~5,000× stake.
Spins 6-20: more Orpheus landings, multiple 3-reel expansions, ~3,000× cumulative.
Total round: capped at 12,075× stake. From a A$1 stake, the maximum A$12,075. The YouTube clip your mates send around. Our max-win deep-dive breaks down the realistic odds and stake-sizing strategy.
Bonus Buy — skipping the trigger grind
Where supported, Bonus Buy lets you pay roughly 100× stake to trigger the free-spins round directly.
| Stake | Bonus Buy cost |
|---|---|
| A$0.20 | A$20 |
| A$0.50 | A$50 |
| A$1.00 | A$100 |
| A$2.00 | A$200 |
| A$5.00 | A$500 |
The same expanding-symbol selection process happens. Same distribution of outcomes. The only difference: you skip the ~220-spin grind to get to the bonus.
Is Bonus Buy worth it? Mathematically, it's typically RTP-equivalent or close to it. Some studios slightly reduce RTP on the Bonus Buy path (Relax usually keeps it at 99%, but verify in-game). The downside is bankroll risk concentration — you spend A$100 in one go on a roll of the expander dice, where in normal play you'd spread that A$100 across 200+ spins.
For streamers chasing content, Bonus Buy is efficient. For casual recreational players, the natural trigger is usually less stressful.
Bonus Buy enabled — where?
| Casino | Bonus Buy on Book of 99 |
|---|---|
| Vegasnova | ✅ Enabled |
| Joe Fortune | ✅ Enabled |
| GreatSlots | ✅ Enabled |
| CasinoRocket | ✅ Enabled (with stake-cap on Bonus Buy purchases) |
All four featured AU casinos enable Bonus Buy on Book of 99 at standard 100× stake cost.
The end of the round
When the 10 (or 20, or 30 with retriggers) spins resolve:
- Total round payout is calculated.
- The win amount is added to your balance.
- You're returned to the base game.
- The expanding-symbol selection resets — next bonus, new pick.
A few casinos show a brief end-of-round summary screen with the total win. Most just return you to base game with the new balance visible.
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Quick FAQ
How often do free spins trigger? Average ~1 in 220 spins.
Can I refuse a free-spins round? No — when triggered, the round plays automatically.
Can I cash out partway through free spins? No — the round must complete.
What's the average free-spins win at A$1 stake? Across all bonus rounds, average is roughly 50-80× stake (so A$50-80 at A$1 stake) — heavily skewed by the rare 1,000×+ outliers. Median outcome is lower, around 15-25× stake.
Do free spins expire if I close the game? No — the unspent free spins are saved to your account and will trigger when you next open the game.
Can the expanding symbol be a wild? No — the wild/scatter (book) is excluded from the expander selection pool.
Does the bonus pay scatter wins too? The initial 3/4/5-book scatter payout is credited at the trigger moment. During free spins, additional book landings only contribute to potential retriggers, not new scatter payments.
What if my free spins trigger and I have insufficient balance? Free spins don't deduct from your balance — they're free. You're guaranteed to play out the round regardless of balance.
About this free spins guide
Bonus mechanics verified across 300+ rounds during April-May 2026 testing across the four featured casinos. Trigger rates and payout distributions are estimates based on observed outcomes; the studio doesn't publish exact figures, but the patterns match Relax Gaming's published RTP and variance ratings.
Gambling responsibly. Free spins are the emotional high of the game — and the most expensive minutes of your session if they fall short. Set deposit limits before depositing. AU support: gamblinghelponline.org.au · BetStop · 18+ only.
Further Reading
Related reading in this guide: