This is important because the decks that have the low rarity challenge run Raichu ex, which the AI will prefer to use, so you can negate all of its damage using this strategy
While it's true that it can be a total and complete blowout, it's also dependent on several factors external to the card: Namely, having a creature on the board, that creature have a large amount of power when the spell resolves, and that creature remaining in play as the spell resolves
More importantly, the set lacks any of the usual full art chase cards that dominate recent expansions
With Averna out, you can snag a land from cards that are exiled when you cascade
Blue doesnt often dabble with sacrifice outlets, which makes Geralf an interesting commander that lets you use blue differently from the typical spell-based strategies