As you complete the Maven’s Challenges, you’ll earn a new type of passive skill point that can be allocated on a special passive skill tree in that region of the Atlas of Worlds. Each of the Atlas’ regions has its own passive tree, and they generally have around 20 nodes to choose from. You can earn up to a total of 10 skill points per Atlas region.
Orb of Unmaking grants an atlas passive skill refund point.
Each region has its own fixed tree, and only applies its bonuses to maps within that region. You earn passive points for each tree separately. However, Atlas respec points (which come from Orb of Unmaking) are not region-specific.
Allocate your Atlas passive skills very carefully in order to obtain the maximum value, because refunding skillpoints requires an Orb of Unmaking that can be expensive. The price of Orb of unmaking is about 9 Chaos Orbs.
Tip: If you are unsure what skills to allocate, close the interface and exit the Crucible. You can allocate your atlas skill points at anytime by opening your Atlas and clicking on the regional citadel button (the icon in the center of the citadel interface).
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Orb of Unmaking can be obtained by completing the Maven's challenge.
How often you want to change your passives is up to the player and what they determine to be profitable.
An Orb of Regret grants a passive skill refund point in the passive skill tree.