X-Demon Slot by Evoplay

Above the standard 5x4 grid sits a hidden extra row reserved for Wild Attack symbols. These symbols never contribute to payline wins directly - their sole purpose is conversion. When a Wild Attack lands on the top row with a high-paying demon symbol sitting in the cell directly below, the demon transforms into a Wild for that spin. Six different demon types fill the high and mid pay positions, and any of them can be targeted by the Wild Attack.

Free spins introduce a collection system that changes the dynamic. Each demon type gets its own meter showing how many more conversions it needs. Every time a Wild Attack hits a particular demon during free spins, that meter ticks down. Once a meter fills completely, that demon becomes a Golden Wild - a permanent wild that stays on the reels for all remaining free spins. Each completed meter also awards 2 extra free spins, extending the round.

The real potential sits in filling multiple meters. With six demon types and enough spins, the grid can accumulate several permanent Golden Wilds across the reels, turning later spins into dense wild-filled paylines. Three Bonus symbols trigger 8 free spins, four trigger 10, and five trigger 12. This is the base version of the dark-themed X-Demon series - a separate Bonus Buy edition exists for players who want to skip straight to the free spins round.