Umbra Stalker

Creature — Elemental

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.

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2008-08-01:
This 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.
2008-08-01:
Chroma 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.
2008-08-01:
Chroma 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.