I don't know why so many people want to balance things by bringing down the successful rainbows... I think balancing should be done by improving the other ones, so that mono, duo, trio and rainbow decks can be equally successful, not equally useless.
If we keep nerfing rainbows instead of improving other decks, there will be no decks capable of even 40% wins against FG. People trying to beat false gods for the first time, with a partially upgraded deck and still little experience in this kind of challenge will have a winning percentage of 5%-10% I guess, or even less, so I wouldn't be surprised if many people simply stopped playing Elements when they see they have to grind for weeks and then lose a hundred times against FG to finally reach a point when fighting FG is more rewarding than draining electrum.
On the other hand you should consider that most FG are duo/trio, so if we add more cards that are good in mono/duo/trio, but poor in rainbows, then FG will become stronger (they will be using better cards and will have better synergies).
This would in fact nerf rainbows a lot - FG become stronger, rainbows stay the same = rainbows are no longer the best against FG
And that idea to make duo-pillars and trio-pillars... I would love that implemented, but there is one HUGE problem... try calculating how many different pillars would be needed, and you will see the point. I'll just remind you there are 144 half-bloods for a reason... and if there were one-third-bloods there would be 1728 of them
In MtG it is possible, because there are 5 colors, so 25 duo combinations... and as far as I remember, they considered that number too big and made only 5 duo-lands (one for each pair of neighboring colors) and 5 trio-lands (for each three colors that are formed by one color and his 2 neighbors).*
In Elements, I guess even that solution would not work, and anyway I don't like the idea of making Elements like MtG.
And if you suggest making only duo or trio pillars for some possible combinations, but leave other combinations without one, I guess that would be unfair.
So does anyone have an idea how to solve that problem?
*(Note to people who don't know MtG:)
duo-lands offer you a choice of either one mana of their first color, or one mana of the second color each turn, not 2 at once
and to keep them balanced they also have the disadvantage that you cannot use them the first turn you play them, and can have only 4 of each kind in the deck (they are not basic lands)
trio-lands offer a choice between three colors, and their disadvantage is that to play one you have to remove one non-trio land you own from play (back to your hand, but in MtG you can play only 1 land each turn, so in fact it gives you a total mana disadventage when compared to your opponent), so you need non-trio lands in your deck anyway, and also a limit of 4 of each kind.