Efficiency, Stars and Ranking
Efficiency is the overall tank efficiency for earning tokens in Treasure battle mode. Efficiency is formed from three components: the rarity of the tank, the purchased stars for the tank, and the level. You can also increase Efficiency by taking part in rating battles and increasing your rank, the higher the rank, the greater the bonus.
Durability has a negative impact on efficiency once it drops below a certain threshold.
Efficiency only works in Treasure battle mode.
Stars are a bonus for increasing the Efficiency of a tank. There are 5 types of stars in total: Bronze, Silver, Gold, Platinum, and Diamond. When buying a star, it is installed in the cell in which it was purchased. If an entry-level star, such as a Bronze, was bought, it can be changed to a higher-class star, but the previous one will be completely lost, without the possibility of transferring it to another slot or another tank. You cannot change stars with a higher level for a lower one. Stars are saved when transferring the tank to other players.
There are 8 ranking ranges with each one having a different bonus to efficiency: