Skill Tree
The skill tree is a way for you to improve your character through small bonuses that add up over time. These bonuses are part of a path that you can choose and follow for your character within the skill tree, be it a more tank and survival oriented build or a more damage oriented build.
Skill tree mechanics
In order to open the skill tree, one must find it on the Others menu, located on the top center in the client UI, like shown in the image. Once clicked, the skill tree will be visible n your screen.
You start from the top, where the wolf's face is located and work your way downwards. The path on the right is damage oriented; the path on the middle is loot oriented and the path on the left is tank oriented. There are no restrictions on what you can get, so build whatever you desire.
As for the points, you can get one point per completed quest, only obtainable for the first time you complete it. You also get points through leveling your character up, getting a point for every x levels.
If you desire to re-do your skill tree at some point, you can hit the Refund Passives button that will remove all of your allocated points and return them for you to spend them again. Be aware that refunding passives has a fee.
It's worth mentioning that you're not stuck in a certain path upon applying a point, so you can freely move horizontally on the tree if you desire to, as long as the nodes are connecting, but be wary of your points, since there won't be many around.