Cheapest priced copy (Core Set 2019): $0.99 at Card Kingdom, near mint, their price list as of .
Valiant Knight 
Creature — Human Knight · 3/4 · Rare · Core Set 2019 · #42
Other Knights you control get +1/+1.
{3}{W}{W}: Knights you control gain double strike until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.99 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Core Set 2019 | 42 | Rare | $0.99 | $1.99Out of stock |
| March of the Machine Commander | 214 | Rare | $0.99Out of stock | — |
| Core Set 2019 Promos | 42s | Rare | — | $1.79 |
2 rulings from Wizards of the Coast
- 13 July 2018Multiple instances of double strike on the same creature are redundant.
- 13 July 2018Because damage remains marked on a creature until it's removed as the turn ends, nonlethal damage dealt to a Knight you control may become lethal if Valiant Knight leaves the battlefield during that turn.