(Although I did have a bunch of Shadowless cards) As you said, there may have been a select few places where this was an exception, but I think peoples view of just how common 1st ed Base cards are is heavily distorted because of the prominence of 1st ed Base in the high-end collecting world
Stain the Mind is not going to be much better than Slaughter Games was I think
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Animists effect also means that simply playing aggressively even attacking with weenies grants you a slow but steady source of increased mana income per turn, allowing you to play more cards or get your big pieces on the field faster
While flying through cyberspace, they are attacked by an anti-virus program which mistakes them for viruses, shooting "vaccine missiles" at them resulting in explosions of bright, rapidly swapping red and blue flashes
Learn more about Set Boosters from the Adventures in the Forgotten Realms product overview and check out the foil-stamped versions of the art cards below (non-stamped versions have the same art without the signature)