Alternative Drop can be obtained from every opponent. It does not matter what opponent you kill. Alternative Drop splits into two types.
Alternative Drop² is a drop, which can be obtained only from a certain level, eg the Blessing Scroll. This can only be obtained when you reach level 50 or more. Alternative Drop² also obtained from all opponents. But it is only available from a certain level.
Alternative Drop³ is a drop, which can be of every opponent, no matter what level is obtained. It requires no special level e.g. Yang obtained from all opponents.
Something about Alternative Drops
If a player has reached level 10 or more above the level of the monster that he kills, the result is that he very rarely gets Alternatively drop.
Player X (Level 1) kill Wild Dogs (Level 1) and receives Yang.
Player Y (level 11) also kill Wild Dogs and receives no Yang, because he is 10 levels over the Wild Dog.