The skill tree in Diablo 4 is literally a tree

 Blizzard has decided to significantly change the skill and upgrade system for Diablo 4 so that classes can have more different builds.

Blizzard has announced that a changed system of advancement and unlocking skills awaits us in Diablo 4. It is still a branched system, with a literal tree in the background, with active and passive skills clearly separated: passive in a circle and active in a square. Depending on the direction of development, passive points are unlocked on the tree, which can activate strong effects at the bottom, ie at the root of the tree.

The idea behind this redesign is that each class has multiple different builds. To this end, Blizzard has decided that players will not be able to unlock all the skills for a single character, but end game characters will have approximately 30-40% of the skills filled out of the total number of them on the tree itself. In fact, the main source of power in the end game segment will come from the very class the player is playing, with the goal of offering players more variety and depth than the current Paragon system in Diablo 3.