Cheapest priced copy (Warhammer 40,000 Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Drach'Nyen 
Legendary Artifact — Equipment · Rare · Warhammer 40,000 Commander · #117
Echo of the First Murder — When Drach'Nyen enters, exile up to one target creature.
Daemon Sword — Equipped creature has menace and gets +X/+0, where X is the exiled card's power.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Warhammer 40,000 Commander | 117 | Rare | $0.49 | — |
| Warhammer 40,000 Commander | 117★ | Rare | — | — |
3 rulings from Wizards of the Coast
- 7 October 2022If more than one card is exiled by Drach'Nyen, usually because its triggered ability was copied one or more times, X is the total power of the exiled cards.
- 7 October 2022If the exiled card's power is determined by a characteristic-defining ability, usually denoted by a "*" in the power/toughness box, that ability applies in exile and should be used to determine the value of X.
- 7 October 2022If the exiled card doesn't have a printed power, perhaps because it was a noncreature permanent that was only a creature on the battlefield due to another effect, X is 0.