Like most apps and sites, TCGplayer could use some improvement in terms of user-friendlessness and some functionalities dont work as they should, but they have one of the most accurate and extensive databases out there and their prices tend to be more accurate as well
1 being the lowest card grade you can receive
What's the most expensive card we can steal
They're usually best used at end of turn on the turn before you, that way you can respond to anything that happens, and if you happen to have mana left over before your turn, draw some cards
If it gains popularity in other constructed formats as some kind of a miraculous combo breaker, then it can go above $5 a piece
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