This will set you back in tempo and can easily cost you the game as a result if in a control deck
Certainly not quite what youre after, but just to get this out of the way: the Dark Arbok card from Team Rocket has an erroneous 1999-23000 Wizards: 465640 77.7 KB This is similar to the Japanese Ancient Mew error which has Nintedo instead of Nintendo
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You can tap this with no mana to shoot an attacking dork for 1 damage but only at the end of the combat step, so you'll take it first
It's not the total mana value of the cards
While I cant find anything confirming why this is, its likely because its on the Reserved List, so Wizards is hesitant to errata something they cant reprint