Cheapest priced copy (Eventide): $0.49 at Card Kingdom, near mint, their price list as of .
Umbra Stalker 
Creature — Elemental · */* · Rare · Eventide · #48
Chroma — Umbra Stalker's power and toughness are each equal to the number of black mana symbols in the mana costs of cards in your graveyard.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.49 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Eventide | 48 | Rare | $0.49 | $1.99 |
3 rulings from Wizards of the Coast
- 1 August 2008Chroma abilities check only mana costs, which are found in a card’s upper right corner. They don’t count mana symbols that appear in a card’s text box.
- 1 August 2008This is a characteristic-defining ability, which means it functions in all zones. You include the symbols in the Stalker’s own mana cost if you need to determine its power and/or toughness while it’s in the graveyard.
- 1 August 2008Chroma abilities count hybrid mana symbols of the appropriate color. For example, a card with mana cost {3}{U/R}{U/R} has two red mana symbols in its mana cost.