Alexstrasza ... ouch. Overpower is brutal. Just looked at it. Low AP cost, 1 Source, and destroy ALL physical armor if you have more than they do? AND Knocked Down for 1 round?
Stripping ALL Physical Armor for 1 Source ... that's powerful. That's an ability that is just ... pardon the play on words, Overpowered no matter how you slice it.
If it was a Pyrokinetic spell that burned away all Magic Armor it'd be just as overpowered.
Even with the limitation of "must have more armor than enemy currently has" it still feels a bit ... broken.
Will I abuse it when I get a toon capable of using it? I'd be stupid not to.