Book of Ultimate Infinity Slot by Light & Wonder

The reel set starts at 3 columns and 4 rows. Land three matching symbols on those first three reels and a fourth reel slides in from the right. If that new reel also lands the same symbol, a fifth reel joins the chain. The expansion keeps going as long as the streak holds, capping at 50 reels in a single round. That's the Infinity Reels engine ReelPlay licensed out, and Book of Ultimate Infinity from Light & Wonder bolts it onto the classic Egyptian Book template in a way that gives every spin two parallel goals.

The second goal is the Book reel. At the start of every base spin, a Book icon is randomly placed somewhere between reels 6 and 15, shown on a small map under the grid. If your growing reels chain stretches far enough to reach that Book reel, you trigger 10 free spins. So a long match streak isn't just paying out on its own. It's also a hunt.

Each extra reel after the initial three also raises a win multiplier: 4 reels gives 2x, 5 reels gives 3x, 6 reels gives 4x, and it keeps climbing with the chain. Wilds appear on every reel except the first and substitute for everything other than the Book and the Growing Symbol.

The free spins round picks one regular paying symbol as the Growing Symbol before the first spin. If that symbol lands on at least two reels during the bonus, it expands to fill each whole reel it touches and pays from any position, not just consecutive. Book and Growing symbols landing on the rightmost reel keep extending the chain. Hit the Book reel again during the bonus (now placed between reels 9 and 15) and you get +10 spins with the same Growing Symbol carried over.