For example, if you control The Ozolith ("Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.") when Zack Fair's last ability resolves, you'll put the appropriate number of each kind of counter onto both The Ozolith and the target creature
If you ran an untap landfall, you can untap them and keep it up
Draconautics Engineer provides a lot of value in an aggressive goblin deck, giving haste to your other creatures, easily becoming a 3/3, and later making a dragon
or, at least, the opponent has had a chance to catch up
At the start of combat, she puts a number of +1/+1 counters equal to her power on one target creature, and that creature also becomes a Mutant