User blog comment:Mohamed7845/Ultor/Deimos Who is Better/@comment-26053138-20150822201237/@comment-26455864-20150822202548

Well, do keep in mind that not everyone has Ultor. As for why they would use a Deimos sub with Tridon, I think it's because Deimos survives much better.

You can get more damage out with Ultor, yes, but being able to survive many attacks is generally favored more. Deimos survives much better due to an HP boosting sphere, an HP boosting ES, and elemental damage immunity. Ultor can get elemental damage immunity by equipping the Impiety Orb, but he loses the effects of the Fallacy Orb, which synergizes great with a taunter (though it isn't necessary).

If the enemy has Ignore Def, then Ultor won't be doing too well, either. Yes, he can survive one round of him taunting due to his Angel Idol, but after that, he can't do much without dying. While the same does go for Deimos, his higher stats can allow him to survive better.

Personally, I don't have an Ultor, so this is all hypothetical, and of course, my opinion.