Ah, that's what it was called and that was what I was planning to use. Forgot the name, since I don't pay attention to the storyline.
And yah, I just noticed that the first ability is useless >_>
EDIT: Great, I don't know how to use an image for the symbol. it looks like I can't import any images so I have to make it on my own.
Screw that, the symbol will just be one giant plain circle.
I don't think it'd be that hard to make something that looks like the medallion.
And, about Micaiah's ability... I don't know, actually. Maybe she can regenerate herself. I'm not too sharp on detailed rules... but as we know, Micaiah can't use Sacrifice on herself like that. Perhaps you could add W to the cost, give her 3/2 instead of 3/1, and let her redirect damage to herself provided it doesn't kill her. Might be a bit lengthy. But Sacrifice keyword plz.