Seth didn't undergo another evolution, he didn't gain another gene skill, nor did he unlock a new ability.
As a matter of fact if one peeked at his stats, it would be clear they were still the same as when this battle began.
What was happening right now was merely an actualization of the power that Seth was always meant to grasp, a perfect convergence of all his attributes.
As they say, only under pressure can steel become a blade.
The constant pressure of life and death had tempered Seth and finally with a mental breakthrough, all the series of coincidental evolutions he had ever undergone collided and converged, each feeding off each other to reflect a greater effect!
The Gene skill Hand of Tide rippled through his muscle mass, fuelling it with currents of staggering might.
The Gene skill Armageddon rippled with black currents that streamed through his being, making his very presence countless times more deadly as the force of annihilation thrived.
