First, the card lacked supply because it was only printed as a buy-a-box promo, which caused its price to spike to absurd levels, especially on Magic Online
Illustrated by Loc Canavaggia Standard Legal Alchemy Legal Pioneer Legal Historic Legal Modern Legal Brawl Legal Legacy Legal Comp
Youve got to build your deck to really abuse it, but if your deck contains 48 artifacts / lands / other colorless cards such as Eldrazi, youre seeing an average of four options per Ancient Stirrings
This has an amazing ETB ability to draw equal to your count of critters equal to your greatest shared creature type
Either way, Space-Time Anomaly is excellent, and is a brand spanking new win condition for the Hope Estheim deck from Final Fantasy
Only if theyre already legal as part of a Standard-legal set if not, they arent