What actually gives you start to level up the tiers in the mission pass?
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You need to earn Mission Stars through completing ARKS Missions to unlock Tiers. You get 5 Mission Stars for completing your Daily ARKS Missions, 5 for completing your Weekly ARKS Missions, and a large amount weekly from the Tier ARKS Missions, with some Tier Missions giving up to 9 Mission Stars.
@AndrlCh Thank you!
ya what AndrlCh said. If you need more info about how it work. here a video that may help https://youtu.be/qGbpo9pihcU