I like the idea of simple Dual Pillars because they're the logical step between regular pillars and quantum pillars. And I personally think any cards named Pillars & Towers that are going to stack should cost 0, because they're resource cards and because of the mulligan rule. If you elmininate the possibility of a casting cost the issue with dual pillars is how they get around being balanced as dual pillars. Do they generate quanta of both types at once, randomly, splash ability, activated conversion ability, etc..
I think my little idea adds a nice bit of strategy, cause if you were to have this type of card out you can control your own quanta generation. Does anyone have a comment on the mechanic of "generating whichever element you have the least of"?
About the maxium possible combinations.. Yes it would be nice to eventually have all 66 in the game. Card distribution is kinda beyond the scope of this thread but maybe dual pillars could be rares distributed through the Half Bloods?