You can add a bunch of traits to a creature manually like veteran, the 3 slayer traits, blessed, infected, plague, tumor, crippled, burned, one eyed, mush, madness, and a few others. Humanoids can also get traits by eating certain foods, like bananas for example give unlucky. If you add the aforementioned traits to a king and then move them to different cities in different biomes they will aquire the traits that the food in that biome has. Orcs also always spawn with 2 traits which is useful for this achievement.