(I don't really remember the names of the card ideas I'll be quoting, if you posted them in the comments it'd be of a great help)
Each Element has a Dragon, aside "Other". This is justificable by saying that Other isn't really an element, however it always has stimulated the designers' minds. Several attempts have been made, most of them weren't successful enough, other seem redunant and likes.
What is the problem? The problem is the cost. It being Other means that it should be payed in
That's however a great problem, Nova generates an incredible amount of quanta in a moment, and if it costs too much it'll be way too expensive to be played. Attempts have been made to solve that problem by making it pay in a specific quanta. That, however, made it even worse because if it was too strong it'd have taken the place of the elemental dragons in monos.
The seemingly right way to do this is by imposing restrictions on it. I kind of remember a more recent card which had the dragon chained and required a great cost in order to unchain it. Another nice idea may be requiring a cost of 4 different kinds of quantum per turn in order to make sure it's going to be played in a good rainbow and make it cost at least 13 in order to prevent nova-dragon (but making possible nova-nova-dragon). Most of those restrictions, though, would make it an awesome OTK companion.
What are your thoughs?