In terms of gameplay, a Foil Magic The Gathering card against a regular Magic The Gathering card has no difference
Kazandu Mammoth / Kazandu Valley Cards ranked around here are generally good on one side with a second side thats at least useable
They arent for every sacrifice deck, but the burst of card draw makes them quite useful, especially if you can recur the sacrificed creature for further value
That said, it will almost definitely be better in Commander, particularly in more aggressive green lists
However, by adding some additional effects to the card especially the part where your opponent loses 2 life --- it makes it so this Mind Rot actually does something even late
You don't get to look at your face-down shields before you put one in your hand, nor do you need to reveal a shield when you put it in your hand