Flipping cards over is not a new thing in Magic–the morph mechanic has been around since the Onslaught block. However, turning a card face-down is very different from transforming a double-faced card. These two effects are very different and do not interact at all (in fact, it’s impossible to ever turn a double-faced card face-down).

Transform means to turn a double-faced card over to reveal the other side. This isn’t a zone change–it simply changes that permanent’s characteristics (usually means a new name, types, abilities, P/T, and mana cost/lack thereof). No matter which face is showing, the card is always “face-up.”

Morph is a keyword mechanic that allows you to cast a card face-down as a 2/2 creature. Additionally, there are a few effects that allow you to look at a face-down creature, turn a face-down creature face-up, or turn a face-up creature face-down.

For example, Ixidor, Reality Sculptor will not give +1/+1 to a Gatstaf Howler, nor can it turn it over so it becomes Gatstaf Shepherd.

Somewhat similarly, Ixidron cannot turn a double-faced card over at all. This is somewhat like the fact that Moonmist won’t do anything to a human that is not double-faced.