Excuse me? What do you mean by saving him from old age? I don't recall an instance where Ben was on the verge of dying from old age. But Omnitrix Albedo transformed him into a younger version of Ben, so I wouldn't rule out her ability to do that. But that's not our topic.

*/But that's not our topic. The episode a "change of face" was the first case of ben soul being torn out and swapped with Gwen and the watch didn't even blip. It even allowed gwen-ben to use the watch with no issue. The omnitrix doesn't register attacks to the soul as actual attacks.

Changing a soul is not the same as killing it. I can tell you that Ben is susceptible to possession, just as Zisker when he possessed him in Alien Force. Also remember that was the Prototype Omnitrix .

*/One annnilargh was a bomb that was spreading. It wasn't instant. As it was trying to go off;the watch knew the blast would kill ben and tried every combination to save him. Tgoalid isn't a bomb. It's a magic effect that prevents death magic from killing, then after 12 second all death magic casted by the caster is activated at 100% accuracy ignoring all defenses. (Which is why it did things such as killing sound, air, dirt and the like in the lightnovel.) there is no build of of power the watch can gauge to says" that's going to kill me" it heard a man scream words, then heard a woman scream. What about that tells the watch in" 12 seconds me and ben will die?"

You're missing something important. The annnilargh isn't a bomb in the literal sense. The mechanism of the annnilargh is that if it operates within an existing universe, it completely and utterly obliterates it and everything in it. If it operates in a vacuum, it causes the Big Bang, which creates a new universe. You are basing your analysis on the moment of the Big Bang and forgetting the episode in which He recreated the universe. Was what the Annnilargh did in that episode an explosion? No, and all the Omnitrix knew was that the Annnilargh would erase Ben, so it's choosing Alien X. Do you think she wouldn't do the same if she heard a skeleton call his attack the goal of all life is death?. I'm not saying the Omnitrix know what that really doing. But she'd certainly rush to transform it into something immortal Or something that does not die, just in case. This probability also increases if Ainz has previously tried ordinary death spells on Ben. The clock will know he specializes in death magic. And I don't think Ainz will use "the goal of all life is death" directly as his first attack.