Amalia seems close to playable on her own, but then you fold in the combo with Wildgrowth Walker and I would be surprised if she does not enable a new top tier deck, similar to what we saw with Rona
And of course, any deck with access to Ephemerate or similar effects can threaten efficient countermagic even after the Sprite hits the board
If that player can't, perhaps because one of those creatures is tapped, or chooses not to, Tromokratis can't be blocked
You want to avoid, for example, taking out a three-mana spell and adding a seven-mana spell, as doing so could throw off the amount of early playable picks players have
Much like the One Ring was lost for generations in the possession of Smagol, this ring may also disappear without a trace
And just look at all those many colors