Which was the first and which was the last set? Did you eliminate all the dragons, even those that only vaguely resembled dragon faces?
NİKOLAY, I didn't keep track of this, so I can only guess. I killed the dragons near the Sylvan Tree first; I think they were black. The last ones were near the ridge separating the areas of different players. They seemed to be green. I didn't kill all of them, but I killed 1-2 groups more than the minimum required.