The doppelganger skill does NOT have any effect at all when copying some skills, e.g., Astrid and Lucas’s first skill; Jet’s first skill. This is probably the case because those skills no longer work when energy or rage runs out. When Faceless uses his first skill, he has no more energy and therefore cannot continue to use Astrid and Lucas’s and Jet’s skills.

Additionally, passive skills aren’t affected by the skill level gain. For example, if Maya’s Queen of Flowers is copied, the passive effect from Maya’s violet skill, Queen’s Revenge, will have the same level. In the case of Maya’s skill, this is probably because the flower that Faceless makes is really still Maya’s flower, and therefore, the flower that he made will activate Maya’s fourth skill when it dies, just like the flower that she makes will.

Note: There are 14 heroes whose skills are less powerful when copied. There are some more who are not worth copying. The copied ability is not much more powerful.