Lightning costs 1,
Lightning Storm costs 2.
Mutate costs 2,
Pandemonium costs 2.
Fractal costs 9,
Mutate costs 2, put them together, you have 11.
That's the reasoning behind the cost.
I question how powerful it is seeing it's an incredibly unpredictable effect-
Everything turns into a singularity, which has a random chance of things happening,
Then all the singularities turn into other random things.
Then again, mutate is weird...