Dragon treasure. In Heroes Invincible 3, the Wise Library is a very useful outdoor building, which can increase the four attributes of visiting heroes' attack power, defense power, knowledge and strength by 2 points, which is equivalent to supporting a good equipment. However, the entry condition is that the hero level reaches 12. However, if heroes learn diplomacy, the level limit can be lowered, and the junior, intermediate and advanced levels can be reduced by 2 points respectively.