I've found this from this post at Mtgsalvation.com. The card is in Spanish and the translated text reads:
Umbra Stalker 4BBB
Creature - Elemental
Chrome - Umbra Stalker's power and toughness are each equal to the number of black mana symbols in mana costs on cards in your graveyard.
A new mechanic, Chrome, is introduced. Here is the original card image: