If this ability has been activated four or more times this turn, sacrifice this creature at the beginning of the next end step
Instead, he'll be in the back, happily running the casino that is your deck
My line of thought back then was its better to have a card in hand I want to cast, than have a creature or land Im not currently using, and while weve seen similar effects printed since then, most of those will be two mana or more (outside of Village Rites)
Brawl Not Legal Vintage Not Legal Timeless Not Legal Commander Not Legal Pauper Not Legal Oathbreaker Not Legal Penny Not Legal Dack Fayden Emblem Emblem Dack Whenever you cast a spell that targets one or more permanents, gain control of those permanents
The rules team shot it down
Beyond just being rare, thanks in part to the limited-run printing of Secret Lair drops, and their Bonus Cards, Mana Vault is insanely strong