Cheapest priced copy (Warhammer 40,000 Commander): $11.99 at Card Kingdom, near mint, their price list as of .
Keeper of Secrets 
Creature — Demon · 6/4 · Rare · Warhammer 40,000 Commander · #78
First strike, haste
Symphony of Pain — Whenever you cast a spell from anywhere other than your hand, this creature deals damage equal to that spell's mana value to target opponent.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $11.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Warhammer 40,000 Commander | 78 | Rare | $11.99 | — |
| Warhammer 40,000 Commander | 78★ | Rare | — | — |