If an effect refers to a card or spell that was foretold, it means a card put in the exile zone as a result of the special action associated with a foretell ability, or a spell that was a foretold card before it was cast, even if it was cast for a cost other than a foretell cost
It is why cards like Necropotence and Dark Confidant are so potent, they convert life into a more useful resource - cards in hand
You can tap it to add one colorless mana, or you can tap it and pay one life to generate one mana of any color, but this mana must be used to cast Vampire spells
If you have lots of cheap spells, you can lower your opponent's life total in a hurry
From there, its usually correct to keep a low curve with multiple 1- or 2-mana cards and a few 3-drops, and your 4-mana cards like Chandra, Torch of Defiance should be your more impactful threats or win conditions
Its still pending like it has been for days