That's why I'm considering decreasing the cost by one more. Then, for 3 entropy, you would get a new mutant each turn (that would average 2.5 attack) with a potentially awesome skill for the drawback that about 1/6th of the time it would die. Can you say "Fractal"?
In addition, the chance of it dieing would be a little less than 1/6 since you could get the skill lycanthrope or growth.
But yes, M+1 is an option too. I'm considering either decreasing the cost, making it M+1, or doing nothing.