Cheapest priced copy (Double Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Rush of Knowledge 
Sorcery · Common · Scourge · #49
Draw cards equal to the greatest mana value among permanents you control.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
4 printings · $0.35 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters | 66 | Uncommon | $0.35 | $0.49 |
| Commander 2014 | 123 | Common | $0.35 | — |
| The List | SCG-49 | Common | $0.39 | — |
| Scourge | 49 | Common | $0.49 | $7.99 |
One ruling from Wizards of the Coast
- 7 August 2020If a permanent on the battlefield has {X} in its mana cost, X is considered to be 0.