Cheapest priced copy (Marvel's Spider-Man): $0.49 at Card Kingdom, near mint, their price list as of .
Biorganic Carapace 
Artifact — Equipment · Rare · Marvel's Spider-Man · #269
When this Equipment enters, attach it to target creature you control.
Equipped creature gets +2/+2 and has "Whenever this creature deals combat damage to a player, draw a card for each modified creature you control." (Equipment, Auras you control, and counters are modifications.)
Equip {2}
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
3 printings · $0.49 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Marvel's Spider-Man Promos | 124s | Rare | — | $1.49 |
| Marvel's Spider-Man | 124 | Rare | $0.49 | $0.49 |
| Marvel's Spider-Man | 269 | Rare | $0.69 | $0.99 |
4 rulings from Wizards of the Coast
- 19 September 2025The number of modified creatures you control is counted at the time the ability resolves, not the time that damage was dealt.
- 19 September 2025A creature that is equipped is considered modified no matter who controls the Equipment that's attached to it.
- 19 September 2025An Aura controlled by an opponent does not cause a creature you control to be modified.
- 19 September 2025A creature with a counter on it is considered modified no matter what kind of counter it is or which player put it on that creature.