Face Down + Hidden Mana

Oh wait, facedown actually gave entrenching too? Wow, that was sillyoverpowerful then, the 76/1 type monsters would have a huge chance of getting that much needed shot in with entrenching... yikes...

Removing entrenching gives a massive 'YES!' from me (considering it usually adds tons to a card's cost anyway), and the 'theoretical' maximum would be very helpful indeed. It would remove an element of how hidden the card was, but it would still make Face Down very useful, without making it a bookkeeping nightmare.