Ive been playing her on ARAM on the pbe, 3 times now lucky me. I love her. Even with just 2 elements she is still ''ín her element'' hihi. Shes just really strong right now. I havent even tried to get water from somwhere because everyone right away said she can only use the 2.
Of course on ARAM they make certain global adjustments to champions, im pretty sure if they give her the 3rd element somehow, she would have to be nerfed substantially. She has to be nerfed anyways im guessing, because her dmg is really high.
Keep in mind that she was designed for Summoners rift, all champions are. She can only use water on the middle part of the map, and without ivern shes limited to 1 element in the base.
Ivern is kinda the same story on aram of course, he cant use his passive at all. And he doesnt need to, with some tweeks to his stats. Twisted treeline im verious curious about! Im pretty sure they will implement some water in the middle of the map mechanic, just like on SR.