From Brotato Wiki
Luck
You have an x% more chance of finding items or consumables when you kill enemies. Also increases the rarity of the items in the shop and level upgrades. There is no limit to luck but there may be a soft cap.
Check Shop to see Luck's effect on shop rarities
Item box spawn chance is multiplied by Luck.
Formula for item box spawn chance:
Enemy_Box_Drop_Chance * (100% + Luck) / (1 + Box_Spawned_This_Wave)
Items
Positive
The following Characters have a higher chance to find these items in the Shop: 
Lucky
| Name | Rarity | Effects | Base Price | Limit | Unlocked By |
|---|---|---|---|---|---|
| Tier 3 | +15 Luck +18 Harvesting -5% Attack Speed -3% Crit Chance |
75 | Win a run with  Entrepreneur |
||
| Tier 3 | +20 Luck +6% Dodge -2% Life Steal |
65 | |||
| Tier 1 | +8 Luck -1 Elemental Damage |
25 | |||
| Tier 3 | +30 Luck -2 Melee Damage -1 Ranged Damage |
75 | Win a run with Lucky |
||
| Tier 2 | +5% chance to double the value of picked up materials +6 Luck +2 Engineering -5% Damage |
40 | 20 | ||
| Tier 4 | +12 Max HP +25 Luck -5% Damage |
100 | Win a run with  Pacifist |
||
| Tier 4 | +3 Max HP +2 HP Regeneration +1% Life Steal +5% Damage +5% Attack Speed +3% Speed +3% Dodge +1 Armor +5 Luck |
95 | Win a run with  Well Rounded |
||
| Tier 1 | +10 Luck -2% Damage |
28 | |||
| Tier 2 | +20 Luck -2 HP Regeneration |
48 | |||
| Tier 4 | +10 Elemental Damage +20 Luck -5 Engineering |
90 |
Negative
| Name | Rarity | Effects | Base Price | Limit | Unlocked By |
|---|---|---|---|---|---|
| Tier 3 | +8 Max HP +3 HP Regeneration -8 Luck |
85 | |||
| Tier 3 | +10% Speed +3% Life Steal -8 Luck |
65 | Win a run with  Speedy |
||
| Tier 4 | +10 HP Regeneration +2 HP Regeneration every 5 seconds until the end of the wave -10 Luck |
95 | Win a run with  Doctor |
||
| Tier 1 | +3 HP Regeneration -2 Luck |
25 | |||
| Tier 1 | +4% Speed -5 Luck |
15 |
Mechanics
These items use your Luck stat to deal more damage.
The following Characters have a higher chance to find these items in the Shop: Lucky
| Name | Rarity | Effects | Base Price | Limit | Unlocked By |
|---|---|---|---|---|---|
| Tier 1 | +25% chance to deal (25% ) damage to a random enemy when you pick up a material |
22 | |||
| Tier 2 | +25% chance to deal (25%) damage to a random enemy when an enemy dies | 30 |
