My group's adventurers just went and got themselves captured and enslaved by a city-state that runs Roman-style gladiatorial deathmatches. They're in the dungeons under the arena, across the hall from their soon-to-be opponents and reigning arena victors, a band of brutal orcs.
I want the orcs to attempt to indimidate the party, but can't figure out what the opposed check or DC should be for each character. An intimidation vs. intimidation contest-type roll doesn't make sense unless the characters decide to use the same tactic (which they likely won't).
In addition, if the intimidation check is successful, what should the resulting effect be in the upcoming battle? The frightened condition seems a little harsh, but I suppose it would work for a very successful roll.
I'm all for preserving player agency, but am of the opinion that becoming intimidated doesn't fall within those boundaries, i.e., I don't think they should have any more say over what scares them than they would on the day's weather.
Another way to rephrase my question (which I don't see adequately answered in similar questions) is: how is the Orc's +2 to Intimidation skill supposed to work in the game mechanically, and what are the range of effects?