The buy price has fluctuated some, but currently Card Kingdom is offering $80 for Revised Given its utility in Commander, the red sorcery is likely to climb ever-so-slowly over time as copies disappear into decks, never to hit the market again.
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Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Not Legal Toolbox Notes and Rules Information for Relic of Legends: You can tap any untapped legendary creature you control, including one you haven't controlled continuously since the beginning of your most recent turn, to pay the cost of Relic of Legends's activated ability
The result is you cast one artifact, and you get two
It doesn't matter if you lose a coin flip and sacrifice Frenetic Efreet while there are more of its ability on the stack
It gets deleted by your opponent, and they draw a prize card
