What chooses which effect the creature is placed in? Random? Your creature vs opposing creature? AP/HP?
The same thing as unnupped Mutation which does "creature turns into abomination, dies or turns into a mutant"
So if we were to place those as percentages: theres a 33.3% chance to turn into abomination, or 33.3% chance into a mutant, or 33.3% to die.
Regression just has 2 possibilities, so it would be 50% VS 50%, i think its also like Permafrost shield where it says "might" it most probably means 50% chance, since it seems to be more succesful than fog shield which only has 40%.
Actually, Mutation's probabilities are:
- (50%) change it to an Abomination
- (40%) change it to a mutant
- (10%) kill
The card seems like a near-instakill, though - no time quantum and you've basically lost one of your creatures permanently if it becomes a Fate Egg. Perhaps have the opponent gain 1 
, to give the Fate Egg a chance to rebirth?
That just wrecks the essence of the card, If i were add the function you suggested, I would have to change it from being a spell to a creature with the ability so then CC essence is still dominant,
but I highly doubt this is OP because you can only use it 6 times as a spell.
I mean cmon, you have Maxwells demon that is instakill, freeze + shockwave, unupped mutation which has a chance
for insta kill,
and skull buckler chance despite it turing the creature into a skelly it still kills it anyway being able to trigger death effect permanents.
I would say that this card is more similar to skull buckler.
Think about it, How many decks are out there that use
? we have graboid rushes, rainbow decks, anydeck with Nova in it, any deck with hourglass.
I think Nova just about covers it alone.
Imagine if I use this (upped) on an opponents photon, it becomes Elite fate egg. Suddenly opponent uses nova on their turn and boom, you have an elite dragon against you or anything else.
The point is, the spell can easily backfire on you, especially upped version.
