The Box of Potential is a item sold by the Travelling Merchant for 3 
during Hardmode. If it is put into an NPC house it will increase the damage, defence, health regen and max health of the NPC living in that room.
Stats:
- +45% NPC damage
- +18 NPC defence
- +2 NPC health regen
- +150 max NPC health
Tooltip:
"When placed in an NPC's house, it upgrades the NPC's stats"