The thicker the bloodline, the more severe the dragonization phenomenon. Those first, second, or third generation Dragonborn, in appearance bear a striking resemblance to oversized gnolls, at six or seven points similar, possessing only humanoid silhouettes, the rest are all giant dragon features.
But none of them have the ability to transform a second time, like the Black Dragoness.
Shanoba still vividly remembers when she first met Gaven; he was purely a Half-Elf, without a trace of dragon bloodline or ability. At that time, he had gnolls as his servants, using purely human methods to control them, instead of dragon-born powers to subdue.
It wasn't until the Dragon Oak Mother Tree granted him a part of the Dragon Soul that his soul underwent some degree of dragonization, unlocking special abilities like Energy Dragon Wings.
Could it be that the Dragon Oak Mother Tree has further granted him even greater strength?