Rex. A single Rex was a challenge as a final boss, while they had to make you fight like 15-20 Rays to make it a challenge.KillerFly

In easy you had to fight nine, i think. and i don't remember how many on very hard but anyway.

Emma had already put a virus into Ray making it a hell of a lot worse and they where'nt complete like the one Liquid/Ocelot was riding.

Ray is much more powerfull and lokks more stylish, so Ray.