What if you have already made in-game purchases in the past? (Through Steam that is)

This is amazing.

Doubt I'll be making in-game purchases, though.

Then this won't apply, the trading cards are steam items.

Can you expand on how we can get these? From cash purchases of TC, boosters, forum VIP..?

For now you can only get them through in-game purchases made in the Steam version of the game.
You are guaranteed to get a card every purchase of an item you make that worths $9-10, but you need to wait as it will be "dropped" rather than given immediately.

Then after you get one card drop, you'll be eligible for booster pack drops, right?

The way you can get them is just not worth lmao. This policy is shit. Just playing the game itself would have been enough.

You're cool?

Also over 1k in a free to play game. Why? You can't sell them cause no one would buy. so why even bother.

Probably guys you would understand that all of that money he made form duels, market and boosters
If you would even checked his market, inv and how much tc he sold already, you wouldn't say a word about he is stupid donator
Btw, thanks for the cards, Nabi, appreciated