Luck is the core stat in Sol's RNG — it determines your chance of rolling rare auras. Without luck multipliers, you can ONLY roll common/uncommon auras realistically. The endgame is all about maximizing luck to chase Mythic auras.
Base luck starts at 1x. With max stacking, players can reach 10x or more multiplier, making 1/100,000,000 auras feel like 1/10,000,000.