Multi class server idea

I have an idea for a private server, you are welcome to steal.

Imagine you level your warrior to level 10 and you now unlock your talents and the ability to cross class, so you go to another class trainer, maybe priest, and attune to their ways. Now you are a warrior-priest but you had to sacrifice one of your talent trees for one of theirs. You chose to swap protection for shadow, which means you now have arms-fury-shadow all your base warrior and priest spells.

You just made a shadow warrior.

A warrior-priest is different from a priest-warrior which gives you so much build crafting and replayability.

If I knew how I would make a server like this myself, but I don't have the time or the skills. So please steal my idea.

Tldr: get spells and swap a single talent tree from another class.