Burning Hell Slot by Endorphina

Collectors make or break this one. The Hold and Win bonus (called Luck of the Devil) triggers when six or more Fireballs and Collectors land together. Standard stuff so far - 20 positions on the bonus board, three respins that reset with each new symbol. Fireballs carry bet multipliers from 1x up to 15x. But a Collector grabs the combined value of every Fireball on the board, plus every other Collector's value, and the originals all keep their prizes too. One Collector on a board with five Fireballs worth 3x each pays 15x on its own, on top of the 15x from the Fireballs themselves. Drop a second Collector and it sweeps the entire board again - Fireballs and the first Collector included. The math compounds fast.

Mystery symbols add fixed prizes at the end of the round: 20x, 50x, or 100x depending on tier. Fill all 20 positions and the ULTRA Jackpot pays 1,000x. Three separate progressive pools - Grand, Major, Minor - sit on top of everything, triggering randomly at any bet size with better odds at higher stakes.

Free spins run 10, 15, or 20 rounds depending on scatter count, and they're retriggerable. What matters here is the expanding Wild behavior. Every single free spin guarantees at least one Wild on reels 2, 3, or 4 that stretches to cover all four rows. That's a locked column of Wilds on every spin, not a random chance at one. Base game Wilds expand too, but only when they're part of a winning combination.

Lucky Time acts as a near-miss conversion for the bonus. When five Fireballs land - one short of the trigger - extra Fireballs drop onto the reels until six appear and the Luck of the Devil fires. Doesn't activate every time, but it turns some of those frustrating almosts into actual bonus entries. Fruit symbols, stacked demons, and card ranks fill the reels against a cartoonish hellfire backdrop. 3 Coin Towers runs a similar Hold and Win core but caps at 1,700x and splits attention across three bonus types - this one funnels everything into the Collector chain instead.