Need some help with an elemental class based system Options

[Dex]

Hello all, sorry for the possible length of this post, I just need some help.
In my current development I'm trying to make an elemental class system based off of the 4 traditional elements:
Fire, Wind, Water and Earth
Each class is aligned with one of these elements. My idea was that each elemental class at say level 30 could combine with another elemental class. (with the exception of fire and water, air and earth) That class begins at level 1 and must also be raised to level 30 at which point a third class is unlocked from the combined ones. they are as follows;
Fire + Wind = Lightning
Fire + Earth = Metal
Water + Wind = Frost
Water + Earth = Wood or Plant (haven't decided on a name yet.)
Any ideas on how I can implement this with the basic game engine? Or any scripts I may need? Any feedback on this system would be greatly appreciated, also if you have any questions about it please feel free to ask!