This tree will branch out to seperate Sub-Skills that you can specialise in.
Along these branches will be many Passive skill which will give you stats and buffs based on the sub-skill that branch is based on.
You will also be able to unlock new, more powerful skills along the paths and branches that help with that sub-skill.
Variety will play a big role in the type of characters you are able to play.
You can combine different sub-skills to assist each other, overall making your character more powerful.
These sub-skills do not need to be based on the same skill branch either. An example of this would be combining Fire magic with Ranged DPS.
With this combination you would easily be able to combine your skills and shoot fire arrows and perform other powerful skills to cause high damage to your opponents.