Using her in this format allows her to partner with a Background, giving your Commander deck a unique flavor that opens a larger card pool for you to play with
I have no info to explain that, but Id love to hear the science about it if someone can explain it
You can either choose something you can actually play, or you can pick something that you dont mind losing anyway to simply thin out your deck a little bit
What about counting foil MTG cards? Foil cards have their detractors, me included (I think theyre tacky and frequently make card art look worse)
Mixed with the right creatures, it can be the heart of a powerful combo deck: Yawgmoth, Thran Physician, plus two undying creatures (for example Geralfs Messenger and Young Wolf) generates a Yawgmoths Bargain sort-of engine, that can be turned to a One Turn Kill adding a Zulaport Cutthroat effect to the mix
Toss in some buffs and you have a nasty Voltron commander on your hands