Skull Cavern rewards preparation: bombs for clearing floors fast, staircases crafted from stone, spicy eel and crab cakes for luck and speed buffs, and rings that stack magnetism and defense. Depth is a function of speed, and speed is a function of gear.
This guide covers floor-by-floor expectations, iridium node density by depth, Qi challenge runs, and the trade-off between bomb-spamming and careful ladder hunting.