Cheapest priced copy (Secrets of Strixhaven Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Hateful Eidolon 
Enchantment Creature — Spirit · 1/2 · Uncommon · Secrets of Strixhaven Commander · #215
Lifelink
Whenever an enchanted creature dies, draw a card for each Aura you controlled that was attached to it.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Secrets of Strixhaven Commander | 215 | Uncommon | $0.35 | — |
| Theros Beyond Death | 101 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 24 January 2020If Hateful Eidolon dies at the same time as one or more enchanted creatures, its last ability triggers for each of those creatures. This includes Hateful Eidolon itself if it's enchanted.
- 24 January 2020If an Aura you control is destroyed at the same time as the creature it enchants, Hateful Eidolon's triggered ability counts that Aura to determine whether it triggers and how many cards you'll draw.