I've heard of these things called reward cards, what's the purpose behind them???

The purpose? To encourage people to buy CSC with a huge amount of real money ;)

Badly, that's how.

They're supposed to be incentive to invest real money in the site but as of late, with how certain things are going and handled, I really would just wait until Pandemic/Masquerade to even attempt such a feat.

It's explained on the Reward Cards page in the Cash Shop dropdown. The prizes in the shop don't expire, but I think the card is changing tomorrow so (if you're going to) you might as well wait to buy CSC. There's usually a bonus CSC weekend when the card changes.

for every $10 worth of CSC you buy, you get a stamp on your reward card. the first stamp is worth 1 point, the second stamp is worth 2 points, etc. getting all 10 stamps awards you a bonus of 5 points, bringing a full card's value to 60 points. these points can then be spent on special items in the loyalty shop, to which new items are added every time a new loyalty card comes out (which is supposed to be about every 3-4 months i believe).

There is a new card coming out this month, pretty sure. So, if people are close to completion, they should do this soon.

Ah, thanks everyone!