Luck affects a variety of chance-based effects and is represented by a 3-leaf clover.
Luck influences many different elements:
- Room drops: Higher Luck gives a higher chance on drops after clearing rooms, going up to 100% guaranteed drops on any room at around 3-4 Luck in Normal Mode, and less than 10 Luck on Hard Mode.
- The chance of chest drops is also greatly increased (and gives chests nearly every time when combined with Guppy's Tail).
- Tear effect chance: The chance of shooting tears with status effects becomes more likely as Luck goes up. This scales up to 100% chance per tear in most cases with enough Luck.
- Most of the status inflicting effects require a very unlikely high number of Luck to activate on every tear.
- Since these effects persist on the enemies for a set amount of time regardless of the Tears stat, a fast rate of fire is often enough to affect an enemy indefinitely.
- Tear items affected by Luck are:
- Trinkets affected by Luck are:
- Celtic Cross: The Celtic Cross grants its invulnerability more often with higher Luck, topping out at 100% at 27 Luck.
- Virgo: The shield activation chance increases with Luck, topping out at 100% at 10 Luck.
- Gimpy: The Soul Heart/Black Heart drop chance upon taking damage increases with higher Luck, topping out at 50% at 22 Luck. However, due to a programming error, Gimpy won't drop any Soul/Black Hearts if you have more than 22 Luck.
- Old Bandage: The Red Heart drop chance when you take a hit increases with higher Luck, topping out at 50% at 29 Luck. However, due to a programming error, Old Bandage won't drop any Red Hearts if you have more than 29 Luck.
- Midas' Touch: Poops have a chance to turn in Golden Poop. That chance increases with higher Luck.
- Slot machine: Slot machines pay out more often with higher luck, but doesn't scale up to 100% payout chance. The increased payout chance is, however, enough to make the machine almost definitely profitable, and Pretty Fly is awarded more frequently.
- Shell game: Shell games pay out more often with higher luck, but doesn't scale up to 100% payout chance. The increased payout chance is, however, enough to make the beggar almost definitely profitable.
However, Luck doesn't affect:
- Fortune Teller and Portable Slot: Unlike Slot Machines, their chance of giving a consumable don't increase with Luck. Only Lucky Foot increases the winning chances with these machines.
- The activation chance of: Fanny Pack, Dry Baby, The Mulligan, Broken Watch, Infamy, Tech.5, Guppy's Collar, Undefined (for ERROR Room or Black Market teleports), We Need to Go Deeper! (for Trapdoor rooms), Pandora's Box (as its effects are predetermined depending on which floor it's used on), and Missing Page 2.
- Content from Chests, Pots, Mushrooms, Skulls, Blue Fires, Purple Fires, Devil Rooms, and Angel Rooms.
- Normal beggars, devil beggars, key masters, and bomb bums aren't affected by Luck.
| Mom's Box
|| What's inside?
|| When used, Mom's Box will drop a random trinket on the ground. While held, increases luck by 1 and doubles the effects of trinkets.
| Latch Key
|| Luck up
|| Increases Luck by 1, grants 1 Soul Heart and spawns 2 Keys.
| Magic Scab
|| HP + Luck up
|| Increases luck and HP by 1.
| Mom's Pearls
|| Range + luck up
|| +1.25 Range Up. +0.5 Tear Height. +1 Luck Up.
| YO LISTEN!
|| Yo listen!
|| Increases luck. Spawns a fairy familiar that points out secret room entrances and tinted rocks.
| Lucky Toe
|| Luck up!
|| Increases Luck by 1.
- Luck up pills increase luck by 1, and luck down pills decrease luck by 1.
- Lucky Pennies increase luck by 1.
- In co-op, Green Baby will occasionally briefly increase luck by 2. Dark Baby will occasionally briefly increase all stats, including luck.