Instructions
Start the "Magic: the Gathering - Battlemage" game. Enter the game's Campaign mode.
Scroll to the wizard Tevesh on the character-selection screen and select him as your character. Only Tevesh is able to get the Sengir card.
Play through the game until you win your 14th battle. After the battle, you receive two bonus cards; one of them is the Sengir Vampire card.