I had been using genocide, but I agree with you, omnicide is more fitting. I just never really considered the word, but I had been previously arguing that not only did she wipe out the Ancients, but all life on the planet, so it fits. I know the game wants me to view Venat in a positive light, but I just can't.
It colours basically everything her lore touches in game, sadly. For example, after the revelation that the Twelve were just more chess pieces put into place to manipulate the world into what she decided it should be/keep it in the broken state she put it in, I really just wish that I could elect not to have a patron deity. :(
