It is a good idea. I think it is balanced because it is fairly easy for the opponent to avoid playing the card. In that case, the most favorable outcome is 1 drain from each creature and opponent loses a draw. Based on my experience with ghostmare, it is usually possible to avoid discarding a ghost, and nightmare is better at filling the enemy's hand than this card.
I will say that the enemy playing the escalation is almost universally a bad idea. Presumably your deck is designed to dump cards, so there is no way the enemy is going to win that fight. So your enemy playing the card is desperation. The 10 poison is suitable to provoke desperation, but I think your opponent can only make that move if he anticipates killing you soon without getting his draw (unless he is packing purify maybe).