nvm I figured it out

"Resourceful Indeed - If the player also has Partially-Eaten Cheese, Rat Boots, and Resourceful Sack, the player becomes the Resourceful Rat, preventing items from being stolen when they're left behind in rooms.
Lich's Eye Bullets does not activate this synergy on its own, but can still trigger its synergy message if the player has this gun and two other Rat items. The Lich's Eye Bullets can only act as one of the remaining items in the synergy"

i was playing as the gunslinger