Cheapest priced copy (The List): $0.35 at Card Kingdom, near mint, their price list as of .
Arrester's Zeal 
Instant · Common · Ravnica Allegiance · #4
Target creature gets +2/+2 until end of turn.
Addendum — If you cast this spell during your main phase, that creature gains flying until end of turn.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | RNA-4 | Common | $0.35 | — |
| Ravnica Allegiance | 4 | Common | $0.35 | $0.49 |
| Ravnica Remastered | 4 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 12 January 2024Addendum abilities of instant spells apply while the spell is resolving, not immediately after casting it. If the spell is countered, you don't get the addendum bonus.
- 12 January 2024If an effect copies a spell with an addendum ability while it's on the stack, the copy wasn't cast at all, so you won't get the addendum bonus.