"Target Creature deals damage in the form of Poison Counters if it's Poisoned."
Right.
After that, I'd say the card could do with a very slight cost reduction to 7 | 6. I think it's just slightly too weak at eight, but I can definitely understand why it's so high; It's certainly a powerful effect.
Good job overall, actually - I like it. The card just needs to be much more clear.