Controlled Mutation

Creature must make a con save against your spell save DC, on a fail they are subject to a chosen mutation for 1 minute. A willing creature does not need to roll a save.

when casting choose a number 0-500, that will be the mutation they creature is affected by, you do not choose the effect but the number. On a critical cast, every creature with in 10ft in affected by the forced mutation spell. If you attempt an effect that may be too powerful for you to control the DM can decide to up the casting DC, if you would have succededed without the harder DC the caster is affected by the forced mutation spell as consequence for trying to control forces beyond his ability. (for example if cast at 3rd level and the DC would be 10 but the DM makes it 13 for this effect, then an 11 would affect the caster with forced mutation.) The DM can use this option at will and does not have to.

At higher levels you Target additional creatures equal to the level cast, 2nd 2 creature, 3rd 3 creatures and so on