when you add new troops on that tile, the camouflage carries on
When you say it carries on, you mean that the original troops remain camouflaged and the new deployments are seen in full; not that all or part of the new deployment is also camouflaged, right? If the card only affects the original deployment, I like it.
if you border the camouflaged troops of your ennemy, and they are attacked by sb's else troops, they should stay camouflaged to you
I'm not a fan of this. When I think of camouflaged troops, I picture them hiding in bushes, trees, buildings, etc. But in order to fight troops have to shoot back, maneuver tactically and advance somewhat to push the attacking troops back out of the territory. I would vote on your idea if not for this.
Your cards are too powerful. Would you enjoy it if someone used them on you? I would not. OnlyThePie said it right, the blitzkrieg should have limits. I like it, but it should be more like a boost to the regular kill rate, to simulate an inspiring speech or some cultural event that boosts the morale of the troops so they fight harder.
However, it is good to put ideas here before the uservoice, so other people can share their thoughts. It would be best to wait until they are perfected to put them on uservoice. Then we can all go and vote on all of them.