Cheapest priced copy (Time Spiral): $0.35 at Card Kingdom, near mint, their price list as of .
Cavalry Master 
Creature — Human Knight · 3/3 · Uncommon · Time Spiral · #6
Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Other creatures you control with flanking have flanking. (Each instance of flanking triggers separately.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Time Spiral | 6 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 25 September 2006Cavalry Master adds only one instance of flanking per creature, even if that creature already has multiple instances of flanking.
- 25 September 2006If a creature without flanking is given flanking by another effect, then this ability will grant a second instance. Similarly, if a creature loses flanking, then it won’t get the Calvary Master instance either.