Cheapest priced copy (Duskmourn: House of Horror Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Demonic Covenant 
Kindred Enchantment — Demon · Rare · Duskmourn: House of Horror Commander · #19
Whenever one or more Demons you control attack a player, you draw a card and lose 1 life.
At the beginning of your end step, create a 5/5 black Demon creature token with flying, then mill two cards. If two cards that share all their card types were milled this way, sacrifice this enchantment.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duskmourn: House of Horror Commander | 19 | Rare | $0.49 | — |
| Duskmourn: House of Horror Commander | 49 | Rare | $0.79 | — |
4 rulings from Wizards of the Coast
- 20 September 2024Demonic Covenant's first ability will trigger once for each player you attack with one or more Demons.
- 20 September 2024The card types in Magic include artifact, battle, creature, enchantment, instant, kindred, land, planeswalker, and sorcery. Legendary, basic, and snow are supertypes, not card types; Horror and Room are subtypes, not card types.
- 20 September 2024Demonic Covenant's last ability will only cause you to sacrifice Demonic Covenant if both cards have the exact same combination of card types. Supertypes and subtypes are not taken into account.
- 20 September 2024Creatures that enter attacking are never declared as attackers, and as such, they won't cause Demonic Covenant's first ability to trigger.