Cheapest priced copy (Foundations Jumpstart): $1.29 at Card Kingdom, near mint, their price list as of .
Wavebreak Hippocamp 
Enchantment Creature — Horse Fish · 2/2 · Rare · Theros Beyond Death Promos · #80p
Whenever you cast your first spell during each opponent's turn, draw a card.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
6 printings · $1.29 to $10.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Jumpstart 2022 | 371 | Rare | $1.49 | — |
| Foundations Jumpstart | 387 | Rare | $1.29 | — |
| Theros Beyond Death Promos | 80p | Rare | $4.49 | $3.49 |
| Theros Beyond Death Promos | 80s | Rare | — | $4.49 |
| Theros Beyond Death | 80 | Rare | $1.29 | $1.49 |
| Theros Beyond Death | 310 | Rare | $2.99 | $10.99 |
4 rulings from Wizards of the Coast
- 24 January 2020An ability that triggers when you cast a spell resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
- 24 January 2020This ability triggers only on your very first spell during an opponent's turn, not the first spell after the card is on the battlefield. If you cast a spell before it's on the battlefield (including if you cast this card somehow during an opponent's turn), the ability won't trigger.
- 24 January 2020In a Two-Headed Giant game, this ability triggers no more than once during each opposing team's turn.
- 24 January 2020If you have more than one opponent, this ability can trigger once during each of those opponents' turns.