Ruan Mei, Geneticist éclat

Each creature card in your hand gains Mutate. The
Mutate cost is equal to its mana value.
Mutated creatures you control have flying.
Whenever a creature you control mutates, Create a 0/0
green and blue Fractal creature token. Put X +1/+1
counters on it, where X is the greatest power among
creatures you control, for each time that creature has
mutated.