I got to thinking a bit back and realized MagnusSerra's true form. She is a lightning elemented Eastern Dragon. Her sisters also have various dragon forms, I shall list them.

GuzziSerra: Fairy Dragon light
MagnusSerra: Eastern Dragon lightning
SieraSerra: Western Dragon fire
AmphiraSerra: Sea Dragon water
MirrSerra: Wyvern earth
EtherSerra: Celestial Shadow Dragon dark
ArmaSerra(Oblivion): Hydra Dragon all elements

I will attempt to make Ref Sheets for all of them.