Some back faces have abilities that allow them to transform back to their front faces, but for back faces like Hades, it's a one-way journey, although some other spells and abilities may still cause it to transform back
It was inspired by an ability of a Vanguard card called Momir Vig, which allows you to discard a card, pay X amount of mana, and put a random creature in play with mana value X
At the beginning of your end step, choose a card at random exiled with this enchantment and put it onto the battlefield tapped
What affects the value of Omniscience
For two mana, Luminarch Aspirant is a 1/1 Human Cleric which gives a creature you control a +1/+1 counter at the beginning of combat on each of your turns
when that occurs, each of those versions typically shows up half as often so that they, in total, show up as often as cards with a single Booster Fun version