The Apprentice Pass is a good program to help you get started.  We all used it.  Many things in this game are not perfect but you will be given a lot of free resources.  Enjoy them.  

Good luck.  

Erm, isn't it that the appentice pass gives blue brews because all 4 starters champs to choose from are all magic affinity, and the advanced one gives red brews because Rector is force?

Yes.

But you don't have to just level-up the starter champs, you have a whole supporting crew to take care of. I'm not sure I understand the reasoning here. 

The idea is you can power level your starter thru brews and get them maxed out as fast as possible to be your campaign farmer.  It's not really viable to level up food champs with brews so generally speaking its optimal to maximize Magic affinity brews for the starter. 

Your starter can't campaign on an island, alone. They have to have support. Maybe I'm just playing the game wrong.

They can once theyve been built enough.  Masteries + 4 pieces of Lifesteal is usually enough to solo at least the lower difficulties.

Since all you can see is this one champion you care about. Let me throw some math at you. 

To get one champ to the 6* rank, six champions must make it to the 5* rank. The one you want to promote and five "food" champions.

Now, for every champion that makes it to the 5* rank, five must make it to the 4* rank. And for every 4*, four 3* ...

So, now we're talking about 6 * 5 * 4 = 120 champs at the 3* rank to get one to the 6* rank. That's a lot of leveling up. 

How many of those do you think are of the Magic Affinity? I'm going to say 80 to 90 of them are going to be Spirit and Force Affinity.

Does just Magic Affinity Brews still make since to you? Mathematically, it doesn't. Just sayin'

Yes im aware of the math.  I'll just agree to disagree but ill pass along your suggestion.

Honestly, I can't help but feel if they were random you'd be here complaining that it doesn't help because you're concentrating on leveling your starter, and need magic brews.

I mean, lemme ask you this: did you use every brew you got? Or do you have a pile of left over unused magic brews? And if so, why didn't you use them to level your starter faster?

Because I'm still trying to get enough other 5* rank champions to rank up my starter to 6*. If that's not a problem for you, please tell me your secret.

My point is that if you used all the brews you had, you still got the same total amount of xp. It wouldn't make a difference if they had been other affinities.