For the item to be considered 100% gold efficient, the passive would need to have a gold value of 67g.
The passive restores health and mana equivalent to 1 health potion and 2 mana potions per level up, this has an equivalent gold value of 105g, meaning the item can be considered gold efficient after one level up.
With the increased durability and sustainability it provides, Catalyst the Protector allows champions to remain in their lanes longer without needing to recall.
Champions at higher levels require more experience to level up, making this item less effective at providing sustainability at later stages of the game.
The word Catalyst means something or someone that precipitates or causes an event to happen without being used up itself, possibly referring to the passive effect that causes massive regeneration whenever a champion gains a level.