I think that the template used in the Unhinged card S.N.O.T., will be very close to what will be used in Planechase, but without using the "^2" in the power/toughness (which, in my opinion, are wrong)
Creature
Devour X
~ power and toughness are equal to the square of the amount of mana spent on X.
*/*
Creature
Devour X
~ power and toughness are equal to the square of the amount of mana spent on X.
*/*