Cheapest priced copy (Invasion): $0.35 at Card Kingdom, near mint, their price list as of .
Explosive Growth 
Instant · Common · Invasion · #187
Kicker {5} (You may pay an additional {5} as you cast this spell.)
Target creature gets +2/+2 until end of turn. If this spell was kicked, that creature gets +5/+5 until end of turn instead.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.35 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Invasion | 187 | Common | $0.35 | $2.99 |
6 rulings from Wizards of the Coast
- 8 November 2024If a spell's kicker cost was paid, the spell is "kicked."
- 8 November 2024The kicker ability doesn't let you pay a kicker cost more than once.
- 8 November 2024If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was.
- 8 November 2024If you copy a kicked spell on the stack, the copy is also kicked. If the copied spell is a permanent spell, the token the copy of that spell becomes when it enters is also kicked.
- 8 November 2024If you put a permanent with a kicker ability onto the battlefield without casting it, you can't kick it.
- 8 November 2024To determine a spell's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases (such as kicker), then apply any cost reductions. The spell's mana value remains unchanged, no matter what the total cost to cast it was.