I don't think Druid is really cut out for a Highlander deck, not in Wild and certainly not in Standard. And if it were, the effect is ok, but not really huge, like Raza the Chained used to be. Not to mention that there are not that many great cards in the class to give up on duplicates that easily.
Some say you could include her just for a combo when you are at/near fatigue. For that to work, you have to have at most 5 cards in hand if you want to copy all the important pieces without overfilling your hand, all while your deck is empty or almost empty. And once you have copied your hand, you need to survive at least one more turn to play your combo.
If you want to go through so much trouble just to set up a combo that could be game winning, why not just play something with Aviana, Innervate and Kun the Forgotten King? If you are ready to draw most or all of your deck, you can also play a combo that doesn't require you to carefully manage your hand on top of making it to the bottom of your deck. You are even allowed to have duplicates left, in case your combo arrives a bit sooner.
And I'm only talking about Wild mode because close to nobody even considers any kind of Control or Combo Druid in Standard right now, despite having Dreampetal Florist and Flobbidinous Floop. Maybe the other cards of the set give Druid massive control power, but I doubt it.
Most people want to put this card into a highlander deck but Elise seems to have better combo potential in a normal deck. Maybe use the miracle package that mechathun druid used, empty your deck with your combo pieces in hand and double any duplicates in hand. You could get 2 maly and 4 moonfire(maybe have maly discounted by florist earlier so you can play both ). With floop and nomi if you play Elise then floop you will have 4nomi and 2 floop in hand. Just some theory crafting.
So far I am disappointed, but we shall see what support Druid gets-if any for this card, because at the moment the payoff is redundant since you can just have the duplicates anyways. I guess you can go infinite with Floop?
It's an interesting and powerful effect, but I am not sure Druid can support a highlander style deck in Standard. They lost cards like Naturalize for single target removal. They nerfed their ramp tools, so you can't empty your hand and refill it with your high end stuff in the mid game. In Wild you play Jade Idol, so this card won't do much there either.
This card is a combo enabler at best when you attempt to draw your whole deck and you don't care about duplicates because you won't have any. But what combo is going to win you the game in Standard?
I mean. This infinetely floops. Which is crazy. Like floop, swipe, moonfire, elise. So you have a swipe, and a floop each turn. Or how about infinite spreading plagues in wild. Moonfire plague floop. Every turn.
To me, floop is the best thing to do with this card.
It's interesting but unfortunately I think it's bad. The reward is pretty nice but not quite as good as say the reno effect I think. Keep in mind if you play a control deck you'll have over half a hand. If you plan an aggro deck this is way to slow and I don't think you can build a 1 of aggro deck.
A highlander druid will be a lot harder to build than a highlander lock as you don't have life tap to draw cards so you can handle all situations with your inferior but larger variety of cards.
Can't see synergies with the released cards, someone needs to theory-craft a combo that requires two legendaries in Standard-mode (where you might use Faceless Manipulator anyway), otherwise why run a singleton deck.
Also the reveal stream showed no card that destroys duplicates, meaning Bomb Warrior is going to have a field day if somehow such deck combo deck becomes tier-1.