When to Pick Phantom Assassin
It is good to pick Phantom Assassin when the enemy team has very little early game magical damage or the enemy team doesn't have the ability to easily gank her. PA is an extremely greedy hero to pick and is countered extremely easily by most heroes. It is also notable that she is countered by an MKB, so it is not a good idea to pick PA against any hero that commonly picks up an MKB, such as Gyrocoptor or Clinkz. PA is countered by heroes like Storm Spirit, Queen of Pain, and Pudge, because they can gank her early and easily. She will have a hard time surviving in lane against heroes like Lion and Lich, but if you get a BKB early enough they will not be a problem.