Read the full thread.
Costs were originally 7 / 5 ... but that pretty much restricts it to a mono-earth or a late-game rainbow. The costs were intentionally lowered, so that this card would see wider use.
read my previous comments, earth has nothing this could use so you have to use on other things. Besides rainbow decks use so few earth quantum it shouldn't be hard to get what you need
you need to balance the cost dependent on effect not by how often it would be used
also why are you telling me to read the whole thread when I was the first person to comment in it and have been making comments in it pretty regularly