Since you're in Simic colors you can ramp up in mana faster than your opponents, letting you cast massively powerful creatures with high mana costs and turn them all into two-for-ones
Or even Mazirek, Kraul Death PriestMazirek, Kraul Death Priest decks focused on artifacts
On the stream, Zakeel Gordon, Executive Producer for the Final Fantasy set, noted that summons will appear at all rarities. This should mean splashy mythic rare summons, and also some nice complexity for Pauper
Suffice it to say that its powerful, and it will give people a reason to play red
As such, Kassandra adds a lot to the board for only three mana
A prime example is this version of Sheoldred, the Apocalypse as "Khan, Engineered Evil," which depicts the incarnation of Khan from the Kelvin timeline