click on booster card Icon
pick unit you want
pick location you want it
click on unit box at location to start. Your unit should show up Mobilizing in location selected

Typically, booster cards are activated by clicking on them, and then you'll be prompted to place them on your country map within certain designated areas or circles. These circles often represent where the booster's effects will be applied. As for using them all at once, it might depend on the game's mechanics and rules. Some games allow you to activate multiple booster cards simultaneously, while others may require you to use them strategically one at a time. If you're unsure, experimenting with different approaches and reading the game's instructions or tutorials can help clarify how to best utilize your booster cards for maximum benefit!