Score Multiplier Pass[]
Score multipliers is a pass that can give you a boost in XP. While in battle, you will get a 30% XP. If you buy it, the lifetime of this item varies between the different types. It can be very useful to level up more quick.
It can be unlocked at any rank and purchased with 
12,500. They can be bought in the garage or gotten as a daily bonus gift. (Recruits will usually get this in the beginning).
In-game description (Golden):
“Increases recieved points by 30%. Lifetime- one month
Attention, score multiplier pass does not give an advantage in team battles.”
What that means is that your SCORE won't increase in a battle, but you will get more XP. Say your score is 200 in a battle. It won't suddenly increase to 260. But, your XP will be increased by 30%.
Different Types[]
Increases XP by 30%. Only lasts one day. Can be recieved as a Daily gift.
Increases XP by 30%. Lasts 1 week. Can be recieved when a player logs in after a long period of absence. The "We Missed You" message usually includes a silver score multiplier.
Increases by 30%. Lasts 1 month. This is bought from the garage.
In-game Description