You cannot buy score multiplier pass anymore.
1. Buy Premium
2. Buy crystals
3. Participate in contests which you can find in the Tanki Online Newspaper
4. Earn them in battles
5. Collect Gold boxes
Hope that helped you and good luck :)
1)The easiest in game way without spending money is to simply do your daily challenges and collect the rewards and containers that come with them.
2)If you have a large amount of supplies, and have a low skill set, you can use them to take the first place with ease.(though this option angers most tankers)
Customer support service by UserEcho