Originally Posted by
crowe_1
I don't feel as though people contort their deck to run Portent; people run Portent because it holds the deck together in a unique way that Preordain didn't. That's assuming five Miracles cards in the deck, with everything instant-speed making the "slow-trip" drawback mostly moot. As you move the deck into a direction that's less "Miracle control" and more "Mentor control" Preordain's stock goes up since you want Mentor and you can only cast Mentor in your main phase. For those running a lot of Miracle cards and instants though, Portent is probably a stronger card because Preordain cannot enable Miracles on its own at all, while Portent does it naturally and we can cast all our spells on the opponents' turn anyway.
You mentioned wanting Preordain for when you NEED a Mentor, and there is no doubt those situations arise, but there's also an an awful lot of times you're behind on board and you NEED a Terminus or Entreat, which Preordain does not facilitate in a timely manner. Basically, if you need Mentor now (or Council's Judgement/any sorcery) you're better off with Preordain, but if you need a Terminus (or any instant), Portent is more useful overall imo. Which you use will probably depend on how the rest of the deck is constructed. But it's all just theorycraft until tested obviously.