I killed one dragon then found a skull went in, killed an iron golem and it said i won after killing it. Game must have glitched since i only killed one dragon.
Also bombs kill dragons in 1 attack so highwayman and shadowknight are the way to go to kill the dragons.
Other than that i always use demon because firebreath does 3 projectiles of 9 damage which is 27 and kills almost anything in 1 attack. Also flying
 "Bullseye (Interstellar Marines)"){kind=icon}
 "Great Dungeon in the Sky"){kind=icon}