MArcomage

For whatever reason, I can't actually play this card. I have it in an AI game I made to test out my decks, but even though I can easily pay it's negligable cost, the game won't let me play it. What's wrong?

You probably played one of AI challenge games. In that mode you can't play rares, though you still can draw it.

If you could post link to your game replay it would clear all the doubts.

Ah, yeah; that's it. Good to know.