You can return this card from your Graveyard to the original owner's Deck, discard 1 card
Youre Invesigators are still trying to advance the Agenda Deck before the Act Deck completes (or the enemies get you)
As a result of this balancing, higher rarity cards are literally rarer and harder to obtain, typically leading to higher prices
Serras Sanctum also saw a swift banning back in the day, though it is currently legal in any format you can play it in, like Legacy, Commander, and Vintage
Since there are currently Pokemon TCG shortages worldwide, it's possible Creatures is intentionally designing fewer new cards to free up printing capacity, allowing more copies of those cards to be produced (or even other sets)
In singleton formats, that kind of precision is why you play it, no matter what MTG color combinations youre running (as long as it includes black)