Cheapest priced copy (Mercadian Masques): $0.35 at Card Kingdom, near mint, their price list as of .
Robber Fly 
Creature — Insect · 1/1 · Uncommon · Mercadian Masques · #209
Flying
Whenever this creature becomes blocked, defending player discards all the cards in their hand, then draws that many cards.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.35 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Mercadian Masques | 209 | Uncommon | $0.35 | $2.99 |
One ruling from Wizards of the Coast
- 4 October 2004It triggers only once even if blocked by more than one creature.