The Soul Stones harness ability is a bit overblown given the massive set-up cost, but it's all gravy on a massive upgrade to Charcoal Diamond, and an indication that the other colors will be getting some improved mana rocks soon enough, probably a few as early as Marvel Super Heroes next year
Instants let you hold your mana and react to whatever your opponent does
But when it comes to actually owning the cards, there are only ten across all of Unglued and Unhinged that most established players want: Other than the gorgeous full-art basics in these sets, most established Magic players I know don't care about Un-sets
TLDR Magic: The Baseballing Secret Lair is a baseball card style Secret Lair drop that turns the original five planeswalkers into collectible sports-card-looking, reversible cards
If you want to min-max Aurelia, then this is likely where you want to be
Of course, this means you need a character on board that can initiate the challenge before Maid Marian gets value, but there are 11 4-cost characters that all have decent Strength values, so it isn't hard to get something down the previous turn that can take the Challenge
