Cheapest priced copy (Double Masters 2022): $0.35 at Card Kingdom, near mint, their price list as of .
League Guildmage 
Creature — Human Wizard · 2/2 · Uncommon · Guilds of Ravnica · #185
{3}{U}, {T}: Draw a card.
{X}{R}, {T}: Copy target instant or sorcery spell you control with mana value X. You may choose new targets for the copy.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters 2022 | 241 | Uncommon | $0.35 | $0.49 |
| Guilds of Ravnica | 185 | Uncommon | $0.35 | $0.49 |
9 rulings from Wizards of the Coast
- 5 October 2018If the spell has damage divided as it was cast, the division can't be changed (although the targets receiving that damage still can). The same is true of spells that distribute counters.
- 5 October 2018The copy is created on the stack, so it's not "cast." Abilities that trigger when a player casts a spell won't trigger.
- 5 October 2018If a spell has {X} in its mana cost, include the value chosen for that X when determining the mana value of that spell.
- 5 October 2018The copy will have the same targets as the spell it's copying unless you choose new ones. You may change any number of the targets, including all of them or none of them. If, for one of the targets, you can't choose a new legal target, then it remains unchanged (even if the current target is illegal).
- 5 October 2018If the spell that's copied is modal (that is, it says "Choose one —" or the like), the copy will have the same mode. A different mode can't be chosen.
- 5 October 2018If the spell that's copied has an X whose value was determined as it was cast (like Banefire does), the copy will have the same value of X.
- 5 October 2018If you copy a spell, you control the copy. It will resolve before the original spell does.
- 5 October 2018League Guildmage's second ability can copy any instant or sorcery spell you control, not just one with targets.
- 5 October 2018The controller of a copy can't choose to pay any alternative or additional costs for the copy. However, effects based on any alternative or additional costs that were paid for the original spell are copied as though those same costs were paid for the copy.