If you're trying to work out whether Book of Evil is worth your time, this hands-on review breaks it down. This is a SpinOn release, sitting firmly in the a medium-variance maths model bracket and paying back a return-to-player rate of 93.65%. It first went live in 2024 and still earns its place today. If everything lines up, Book of Evil can pay up to 5,000x your bet. Visually it's themed around halloween, with the action running on 5 reels and 20 paylines. The full verdict is below.
Written by Daniel Chen · Last updated: February 2026
Book of Evil comes to us from SpinOn, dressed up with a halloween theme and powered by 5 reels and 20 paylines. The result is a medium-variance maths model paired with an RTP of 93.65%.
Where Book of Evil earns its keep is the feature set. Look out for scatter symbols that unlock free spins and extra bonus rounds. The medium volatility strikes a middle ground that should suit most playing styles. On balance, Book of Evil is a dependable option worth a few spins in the demo first.
The RTP of 93.65% is below the industry average of ~96%. This is common for older slots or those with special features. The lower RTP may be offset by unique mechanics or higher maximum win potential.
A balanced volatility profile with a mix of smaller frequent wins and occasional larger bonus payouts. Suitable for players who want steady action without extreme swings.
About 1 in 3 spins results in a win. This is a moderate hit frequency that balances win frequency with payout size.
Book of Evil features scatter symbols that can trigger free spins rounds. Landing the required number of scatter symbols anywhere on the reels activates the free spins feature, giving you extra chances to win without additional bets. During free spins, special modifiers may apply to boost your winning potential.
3.0 / 5 — Good
Book of Evil by SpinOn is a solid offering that delivers good entertainment value. The 93.65% RTP combined with medium volatility creates a well-balanced gaming experience.