Idea is simple. It's a high price, high grade consumable that reduces damage received from premium ammunition.
It automatically actives for the duration of the entire match, like food. Unlike food, however, it is consumed after battle only if the player received at least one golden hit. Having to pay only when it gets used will make the consumable approachable to all kinds of players and tanks. While for T10 superheavies, the rate of consumption will be effectively once per game anyway.
The damage reduction value and cost are up to game designers, but I'd expect the reduction value to be minimal (10% – 20%) and cost to be excessive.
Yes, this proposal benefits "the rich." However, all equipment and all consumables, as well as obviously, premium ammunition benefit the rich. In fact, it fits nicely into the power economy already established in the game.
I'd like to hear arguments for and against!