White Dragon is a battle within Final Fantasy 16 where during the main story quest Fire in the Sky, you run into an ice-imbued dragon terrorizing the streets of The Crystalline Dominion.

So, it seems pretty clear, at least, that for the characters in House of the Dragon, the white hart is a symbol of royalty. A man who is clearly less than thrilled to be out hunting.

You will fight a few Dragon bosses in Final Fantasy 16, and White Dragon is one of them. You will face White Dragon in the Crystalline Dominion in Fire in the Sky quest.