Help for a newbie?

I'm seeing people talking about 10 different strategies and 7 different units that I have not purchased yet. Are most of these premium or are they available for purchase in the non-premium, because currently all I see is 6. Do I unlock things as I rank up?

I mean, I don't see most of them. I know how to upgrade.

You can buy all upgrades at a higher price but some strategies are premium only (Iron Fist being an example).

Okay, but I only see 10 available for purchase. Why don't I see all, even in the premium section?

Because the game is like that: it only let's you see the upgrades you have enough points to buy

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