From Brotato Wiki
Fairy
Item
Tier 3
Stats
+1 HP Regeneration for every different Tier I item you have
-2 HP Regeneration for every different Tier IV item you have
-2 HP Regeneration for every different Tier IV item you have
Price
85
Unlocked by
Win a run with 
Renegade
RenegadeItem
Fairy is an in-game item that can be bought from a Shop or can be found in a Crate. Most Items modify the Stats of the player, and some of them provide additional effects.
Unique
Fairy is a unique item. Only 1 of each unique item can be equipped, and it will then no longer be offered in the Shop, and no longer drop from loot crates.
Fairy
As of Version 1.0.1.3 there are 53 unique Tier I Items and 31 unique Tier IV Items . Therefore the maximum possible +HP Regeneration is +53 (all unique Tier I, 0 Tier IV), the minimum possible is -62 (0 Tier I, all Tier IV), and the Fairy is a net negative of -9 HP Regeneration if you have all unique items for both Tier I and Tier IV.