Zac

Zac enters the battlefield with X +1/+1 counters
on it.
When Zac dies, create X 0/1 green and blue ooze creature tokens with 'At the end of turn sacrifice me
to return a creature names Zac to the battlefield. If you already have one, put a +1/+1 counter on it instead.'
Where X is the amount of +1/+1 counters on Zac.
{4}{u}{g}: Monstrosity 4