Book of the Priestess Slot by Evoplay

Ten paylines on a book-of game is standard territory, and the core loop follows the formula closely - three Books trigger 10 free spins, one symbol gets selected to expand, and that expanding symbol pays across non-adjacent reels. Where this one separates is the Ancient Mask counter sitting above the grid during free spins. Each Book that lands in the bonus ticks the counter down from 7. Hit zero and a second symbol joins the expanding pool, 5 extra spins get added, and the counter resets. The cycle keeps going until all 9 regular symbols expand or the round dies out. The mask is the retrigger, and it demands Scatters keep showing up inside an already-running bonus.

Without a buy bonus option, triggering comes down to base game Scatter landings. The dark cracked-stone reels sit inside carved golden Mayan pillars, tropical canopy pressing in from both sides. Two character portraits - the Priestess with auburn hair and a red-feathered headdress, and a green-plumed warrior with a golden mask - sit at the top of the paytable with a steep gap between them. The Priestess at 500x for five is more than double the warrior's 200x, and everything below drops off fast to 75x and under. That top-heavy paytable makes the random expand selection at the start of free spins matter more than usual.

The Book symbol glows with a teal gemstone clasp and cyan energy trails when it lands, doubling as Wild for base game line hits. During free spins, though, it stops substituting for the chosen expanding symbol - it only feeds the mask counter. So Books in the bonus are valuable for progression but won't help complete expanding symbol combos directly. The Bonus Buy edition skips the base game grind at 87x, but this version is the one where the trigger comes naturally.