While it's arguably more difficult to pop Marit Lage's Slumber than it is Dark Depths, the bonus Scrying it'll provide a Snow deck helps ensure subsequent draws are smoothed out on our way to a Lovecraftian behemoth
Its colorless, and it gives you a spell from the discover ability the turn you cast it, so its fast enough
While white-blue is often a control deck, it leans more towards tempo in this set, meaning it uses its effects to get damage through to win the game more quickly
Having those creatures return to your hand isnt ideal, however
But thankfully Sythis isn't so good that she invalidates the other Enchantress options like Tuvasa the Sunlit, Daxos the Returned, or even the other Selesnya powerhouse, Siona, Captain of the Pyleas
You can view every Legendary card in Disney Lorcana in our card database