I read you check the hitpoints on them, how do you do it? With a special pen? And how do you clean afterwards?

I'm worried because if it's not really high quality, and stains, it will ruin my game :/

emikanter said:

You use a dry erase marker.  You can wipe the marks off very easily with tissue, paper towel, cloth or even your finger.  These types of markers are easy to find and don't cost much.  They will not harm your cards.

i used a dry erase pen with no problem

How big are the unit cards? I was thinking of putting them in plastic sleeves and us markers on the sleeves.

4 x 6 inches - so twice the size of normal playing cards

Cards are large, high quality, including the lamination.  I use dry erase marker with absolutely no staining or other problems.  Card sleeves are completely unecessary.  Good thing, because you won't find any that will fit. 

I'm not going to mark the cards. Just going to use dice for showing how many hits and limited ammo are left.

 I guess you could just photo copy the cards and then just bin the used ones after every game ???

I bought some mylar 4 MM post card sleves from the2buds for my cards. They are very nice.

I understand the concern with the cards but with a dry erase marker, i have experienced no problem.  I also use tokens to mark the cards of those units that have been activated.  I dont like the idea of turning them over.

Dcal12 said:

I just move the cards to one side as I actavate them. 

I agree with Dcal. If you use dryerase markers there will be no issues. Just remember to not let the marks you make remain on the card over a long period of time, (several days) as the some brands of markers have a habit of staining. But if you clean them right when you are done, your issues will be nil.