Ruan Mei, Geneticist éclat

Each creature card in your hand gains Mutate.
The Mutate cost is equal to its mana value.
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.
Mutated creatures you control have menace.