A poisonous minion was generated from the 3 Mana 4-4 minion that gives your opponent a random 4 cost minion. That was used to destroy the pinata in the tavern brawl. Once it was “killed” the game didnt end, a crater with the remaining stats of the pinata remained on my screen and the gamestate would not progress. I could play minions anywhere on the screen and they would stay there, the hero power that does 3 damage to the pinata did nothing, and my opponent and I were basically stuck with no way to progress the game
You have to kill the pinata by doing x damage. Using a poisonous card to kill him early bugs the game out.