Cheapest priced copy (The Lost Caverns of Ixalan Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Deeproot Waters 
Enchantment · Uncommon · The Lost Caverns of Ixalan Commander · #152
Whenever you cast a Merfolk spell, create a 1/1 blue Merfolk creature token with hexproof. (A creature with hexproof can't be the target of spells or abilities your opponents control.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan Commander | 152 | Uncommon | $0.35 | — |
| Ixalan | 51 | Uncommon | $0.39 | $4.99 |
2 rulings from Wizards of the Coast
- 29 September 2017The ability of Deeproot Waters resolves before the spell that caused it to trigger.
- 19 January 2018If an effect refers to a "[subtype] spell" or "[subtype] card," it refers only to a spell or card that has that subtype. For example, March of the Drowned is a card that benefits Pirates and features Pirates in its illustration, but it isn't a Pirate card.