Thanks for the reply! Poison can become annoying if you try to play a slower deck (Mystic specifically, as it bypasses armor). It basically forces you to rush things down, limiting options and strategy. Cleanse would solve this issue I think.
Also I would suggest having a look at "The Rich Get Richer", it feels way too powerful, especially when combined with "Money is Power". Other than this the cards feel really balanced!
Keep up the good work :)