Cheapest priced copy (Avatar: The Last Airbender Eternal): $2.99 at Card Kingdom, near mint, their price list as of .
Heartbeat of Spring 
Enchantment · Rare · Champions of Kamigawa · #212
Whenever a player taps a land for mana, that player adds one mana of any type that land produced.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $2.99 to $10.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters | 171 | Rare | $3.49 | $4.49 |
| Champions of Kamigawa | 212 | Rare | $5.49 | $10.99 |
| Secret Lair Drop | 1010 | Rare | $3.49 | $4.99 |
| Avatar: The Last Airbender Eternal | 42 | Mythic | $2.99 | $4.49 |
3 rulings from Wizards of the Coast
- 7 August 2020Heartbeat of Spring doesn't care about any restrictions or riders your lands put on the mana they produce, such as those of Unclaimed Territory and Cavern of Souls. It just produces one mana of the appropriate type, with no restrictions or riders.
- 7 August 2020The types of mana are white, blue, black, red, green, and colorless.
- 7 August 2020If you tap a land for more than one mana, you choose one type that was produced and add one mana of that type.