Taking in extra affiliated energies to increase output, but just from a simple formula, it was derived to be able to take in other forms of energy.
Gemscales are able to. WERE able to in the past, efficiently take in elemental energies equivalent to the redscales or the bluescales, any scale. As such, it was also possible BEFORE when they had more ADEPT druids to enter a.. fused state with Azerai. They were able to do that with usually any, but yet again, it depended on the individual summoner's affinity. For example, one who has more affinity with WIND or to a lesser degree WATER, would have a far more difficult time trying to fuse with one of fire or earth.