If nothing unexpected occurs, when one has evolved to the advanced state of their race, they generally do not evolve any further.
No matter how many Soul Fires one consumes, it will only strengthen the body to a certain extent, without further evolution.
But some undead creatures with extraordinary talents will break this norm.
Even when they evolve to the highest state of their race, they do not stop their journey of evolution.
Although evolving is much more difficult compared to other undead creatures of the same tier, as long as they can absorb a large amount of Soul Fire, there is still a chance for evolution.
This phenomenon is known as rank advancement.
For instance, a Bronze-tier skeleton has a chance to advance to a Black Iron-tier Skeleton Warrior, thus escaping the dismal fate of being mere cannon fodder.
Black Iron-level zombies have a chance to advance to Bronze-level Advanced Zombies, becoming more powerful in combat.
