Just got hit with a “0” card combo in bracket 2- What do you guys think?

Just played a bracket 2 game where one of my opponents had \[\[Caradora, Heart of Alacria\]\] as their commander. They played a bunch of mana dorks, and ended up playing their commander twice. The two cards they searched for from commander were \[\[Mutable Explorer\]\] and \[\[Guardian Sunmare\]\]. From the guardian, they searched \[\[The Book of Exalted Deeds\]\]. Using the book, they put the counter on the changling manland and it was impossible for the rest of us to win without land destruction.

How would you guys feel about encountering this combo in bracket 2?