In Modern, this is a great way to cast a giant Eldrazi early in the game
Aesi, Tyrant of Gyre Strait is a big beast that would cost you around $10 on its own, while Giggling Skitterspike and Ashaya, Soul of the Wild arent far behind
Choices made for permanents as they entered the battlefield are remembered when they phase in
Which makes a ton of sense since there are some great reprints in the precon, with Veyran, Voice of DualityVeyran, Voice of Duality, Monastery MentorMonastery Mentor, and Archmage EmeritusArchmage Emeritus
Like most other alternate costs, you can't choose to Evoke a creature if you're using an effect that allows you to cast it without paying its mana cost
Meaning the person who snagged one for just $10k can feel much better about their auction acumen