Cheapest priced copy (Guildpact): $0.99 at Card Kingdom, near mint, their price list as of .
Abyssal Nocturnus 
Creature — Horror · 2/2 · Rare · Guildpact · #43
Whenever an opponent discards a card, this creature gets +2/+2 and gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.99 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Guildpact | 43 | Rare | $0.99 | $2.99 |
2 rulings from Wizards of the Coast
- 1 February 2006If your opponent discards any cards during their cleanup step to get down to the maximum hand size, the ability will trigger and players will receive priority. After that cleanup step ends, a new one will begin and Abyssal Nocturnus's effect will end. It won't carry over into the next turn.
- 1 February 2006If your opponent discards multiple cards to a single effect, this will trigger multiple times.