Jumpstart boosters usually sell for around $5-$7 and contain 20 cards: one rare from the theme (sometimes two), some uncommons, commons, and 8-9 basic lands
It is also important to have some Tourachs Canticle for the slower matchups
For example, Doom Blade reads Destroy target nonblack creature. You cant cast Doom Blade targeting a creature with hexproof
Learn about Magic's archetypes and see how cards from Foundations fit those decks
For deck-building purposes, they're treated as another copy of the card indicated at the bottom of the card. WotC says that the cards will be available at Wizards Play Network stores and will only be available in English, but the company points out that they have plans to partner with local game stores around the world to bring some Secret Lair offerings their way as well at some point in the future
But its ability to force your opponents creatures to attack so that you can swing against an uncontested board on your turns really is fantastic