That being said, it would be a pretty easy card to counter... reverse time and poof. Then your opponent has a creature they can't play because, as I understand, the only way to get this on your field is by fusion.
When you get a Nymph off a Pillar, Reversing it makes a Nymph appear in your hand, not a Pillar.
Not to mention Malignant Cell.
One of my favorite false god matches I ever had involved having my field completely swarmed with Malignant Cells, and slowly sending them back into my deck with Eternity. I eventually had an entire hand full of Malignant Cells and started having to discard them
It wouldn't make sense not to have it go back into your deck as normal.