Hydra Ooze

Hydra Ooze enters the battlefield with a number
of +1/+1 counters on it equal to the amount of
mana spent to cast it.
If damage would be dealt to Hydra Ooze while it
has a +1/+1 counter on it, prevent that damage
and remove that many +1/+1 counters from it
and create a 0/0 green Hydra Ooze Head creature
token with that many +1/+1 counters on it.