Cheapest priced copy (Modern Horizons): $0.35 at Card Kingdom, near mint, their price list as of .
String of Disappearances 
Instant · Common · Modern Horizons · #72
Return target creature to its owner's hand. Then that creature's controller may pay {U}{U}. If the player does, they may copy this spell and may choose a new target for that copy.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons | 72 | Common | $0.35 | $0.49 |
4 rulings from Wizards of the Coast
- 14 June 2019The copies String of Disappearances creates are created on the stack, so they’re not cast. Abilities that trigger when a player casts a spell won’t trigger.
- 14 June 2019While resolving String of Disappearances, you can’t pay {U}{U} multiple times to copy it multiple times. It’s a string, not a web.
- 14 June 2019The copy of String of Disappearances has the ability to copy itself. The string can go on or not, as long as players are able and willing to keep paying {U}{U}.
- 14 June 2019If the target creature is an illegal target by the time String of Disappearances tries to resolve, the spell doesn’t resolve. That creature’s controller can’t pay to copy String of Disappearances.