You cast Eldrazi cards from outside the game as part of the resolution of Spawnsire of Ulamog's last ability. You may cast those cards in any order. Timing restrictions based on the card's type (such as creature or sorcery) are ignored. Other restrictions are not (such as the one from Rule of Law). You cast all of the cards you like, putting them onto the stack, then the ability finishes resolving. The spells you cast this way will then resolve as normal, one at a time, in the opposite order that they were put on the stack. They'll remain in the game for the remainder of that game.