Morituri te salutant/salutamus

Certainly if you were talking about the gladiators from the comfort of your chiseling booth while the animals and gladiators were safely locked up in their cages then you would use the third person salutant. If you were one of the gladiators about to die you would use the first person salutamus.

The first time I remember seeing the word morituri it was as the title of a movie about a Japanese ship during World War II and since I thought (erroneously) at the time that it fit the form af a possible Japanese word (it would have to have been Moritsuri as I now understand these things, I may still be wrong) I thought that the word was Japanese.