Blue had flyers, which couldn't block shadow creatures, and green and red had non-shadow creatures which couldn't block shadow creatures or flyers
Well, you can play a burn deck that can potentially have self mill as an alternate win condition
Card cycling is never a bad thing, on top of that this effect can trigger 2 of the major mechanics in the new set Madness (which lets you cast a spell for a different cost if it is discarded), and Delirium (which generates an effect based off card types in your graveyard)
This Magic: The Gathering card is a Green/White card
In the context of the Commander precon to which it belongs, this card is expectedly tailor-made to trigger the commander's ability
According to Wizards of the Coast, this is a printing error which was never corrected, as all card backs have to look the same