Cheapest priced copy (Crimson Vow Commander): $0.79 at Card Kingdom, near mint, their price list as of .
Imperious Mindbreaker 
Creature — Human Wizard · 1/4 · Rare · Crimson Vow Commander · #71
Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Imperious Mindbreaker is paired with another creature, each of those creatures has "Whenever this creature attacks, each opponent mills cards equal to its toughness."
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.79 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Crimson Vow Commander | 33 | Rare | $0.79 | — |
| Crimson Vow Commander | 71 | Rare | $0.99 | — |