Sacrifice (or Sac) is a Magic: The Gathering keyword that describes the act of moving a permanent to its owner's graveyard
That said, the three-color Wedges are important this set, so Ive broken down the Multicolor section of the review into Abzan, Jeskai, Mardu, Sultai and Temur to cover those more powerful cards together
Although Lifestream's Blessing's full potential only activates by paying its Foretell costs, keeping the card handy for the moment you set down a massive creature is a great way to avoid its cancellation while acting as an insurance policy for your life total
Lots of Spellslinger decks add Red which gives you more ways to loot away flashback cards to cast from your graveyard later on, like Faithless Looting, but also powerhouse Spellslinger cards like Increasing Vengeance, Seize the Day, and best of all Past in Flames
As for Sam, Lotal Attendant, he is a 2/4 creature that creates a food token at the beginning of combat on your turn