Everchange Mutant

As long as Everchange Mutant has a +1/+1 counter on it, it has hexproof. This creature enters the battlefield with a +1/+1 counter.
{0}: Everchange Mutant gets +1/-1.
{0}: Everchange Mutant gets -1/+1.
{u}{g}: Put a +1/+1 counter on Everchange Mutant.