From Brotato Wiki
XP Gain
"XP Gain" is a hidden Item Tag for certain Items in the Shop. It's applied to items related to gaining XP (to level up faster and acquire more Upgrades).
The character(s) 
Apprentice, 
Mutant have a higher chance to find these items in the Shop.
Items tagged with "XP Gain"
| Name | Rarity | Effects | Base Price | Limit | Unlocked By |
|---|---|---|---|---|---|
| Tier 3 | +40% XP Gain -2% Life Steal |
70 | |||
| Tier 2 | +25% XP Gain +3 Melee Damage -8 Luck |
50 | |||
| Tier 4 | +10 Engineering +20% XP Gain -3 Max HP |
80 | |||
| Tier 1 | +20% XP Gain -8 Range |
30 |
