Plaguebringer, the card which replaced Vanish in the basic set, is in my opinion a very poorly designed card. Constantly with their talk about class identity, Blizzard talks about how the Basic and Classic sets should give new players a good example of what a class does and what it's strengths and weaknesses are in a fairly simple manner. The Basic set especially should be very easy to understand, since those are the first cards a new player will have access to. So why, then, does Plaguebringer make use of the Poisonous keyword when no other card in the Basic set mentions it? This would lead new players to believe that Rogues are good at abusing Poisonous minions, which hasn't proven to be the case. They only barely have the most Poisonous minions/generators of all classes (Rogue has 7, Hunter has 6, Druid has 5) and as far as I know, only one of which (Envenom Weapon) has seen any serious competitive play in Kingsbane Rogue. I would be fine if this card we're in the Classic set, but I think it's a very poor design for a Basic card.