When the Trove content expansion, Eclipse, launches, it will bring the new subclass feature on board. When players reach level 10, they'll have the ability to unlock a subclass that's based on any one of the other 15 classes. A stat boost and a passive skill will also unlock.
The effectiveness of the passive skill is based on the active Power Rank of the associated class. For example, if you select the Candy Barbarian Subclass and your Candy Barbarian is Power Rank is 2,000 that will determine how much of an attack & movement speed boost you get.
Once a subclass is chosen, it moves to the top of the list of choices, though players can opt to change subclasses at will without cost.
You can head to the Trove site to check out the full list of subclasses.
