The problem is the probability of drawing a card compared to drawing another card is different than the probability of drawing a card compared to not drawing it.
Following the example with 13 pillars and 6 of every other card (though I'm not sure how that can add up to a 30 card deck..so we'll say 31 cards).
13/31 > 6/31, but 13/31 < 18/31.
Therefore you are more like to draw a pillar than any other specific card, but you are more like to draw any other card in general than a pillar.
To figure out your average starting hand, you take each card proportionately to how many of that card there are total.
Example:
You have 12 copies of card A, 6 of card B, 6 of card C, 3 of card D, and 3 of card E for a 30 card deck.
So in any 10 given cards, you are likely to have 4 copies of card A, 2 of card B, 2 of card C, 1 of card D, and 1 of card E.
This means in a 7 card starting hand, you should have 2.8 card A, 1.4 card B, 1.4 card C, 0.7 card D, and 0.7 card E.
This rounds to averaging 3 card A, 2 card B or C and 1 of the other, and 1 card D or E.
But this is all probability, so the actual numbers will usually be different.
I think I hurt my brain too much thinking about something that's not gonna help anyone.
As a general rule: The more copies of a card you have, the more likely you are to draw one.