I recently played with a guy who had a deck full of vampires and whenever one of his vampire attacks/deals combat damage/etc that vampire or all of his vampires get +1/+1 counters.

How can I effectively counter that strategy? I was thinking about cards like [Hex Parasite](https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Hex%20Parasite). My deck is mainly green/red but I'm open to new ideas.