Don't just challenge him to a duel. Don't just challenge him to a duel. (Her ears twitch in annoyance.)

"It's not like I'm messing with your existing operations. You notice I didn't hurt any of the people you are protecting. I think it is a much politer message than violence."

“And I appreciate it. You notice your hired menials were returned unharmed too. We’re professionals, keep things polite.”

”Here’s what you need to know about messing with our existing operations. Your crew builds in our territory. Doesn’t pay us a cut, runs around for a few days before we can even get a meeting. If everyone gets the idea they can get away with that…makes things inconvenient for us.”

"I wouldn't call it returned so much as retrieved. I do admit I didn't get around to introductions on my first day here. It was only me at first, and I had a rather full day. For that I apologize. Still, you expect me to be waiting to hear the shiny little bell, like a maid? It's-"

She huffs. 

"We can keep talking around and posturing for a while, but I'm pretty tired of it after that bird, so- How about a demonstration? Not an attack, still a truce. I'll put it right in the center of the space between us." The tip of her tail lights up with embers, still slowly swaying.

“What bird? Sorry did you have a more important—“

He motions for the other two to step back, and takes a more steady posture. Armor makes a few clicking noises. “Try it. Let’s see the not attack.”

This would be easier if she were more rested, but she didn't expend everything in the rescue, and had another night of moonlight since then. The moonlight dance is a long-worn habit of hers. It's soothing.

But anyway. Time to make this a show. She puts on her full angry otherworldly spirit ensemble in successive illusions: A pale white glow that shimmers from her eyes, highlighting a piercing silver pupil, and fur mixed with streamers of roiling blackness, a subtle sense of volume that puffs her up just a bit, making her seem that much larger. A low infrasound, below the conscious audible range of most people, that seems to fill the air with tension. A slight change to her fangs and claws, showing how prominent and sharp they are. A faint wind that only affects her and flattens the grass just around her. The absence of other background sounds.

And she flicks her tail forward and the embers become a swirling column of flame about five feet across, orange-red shot through with blue. Everyone can feel the heat on their faces and the rush of violent noise and see the sheer brightness of it (all of these slightly, subtly maximized by illusion).

She lets it spin for a good ten seconds, then stops feeding it. The remnants of the flame rotate for another moment before vanishing, leaving a column of warm air and a few smoldering embers around a large patch of earth that has been all but turned to glass.

And her personal special effects cut out too. With a nice little ending animation. It's the little touches that make it believable.

"As for your 'what bird' question, that would be the Minister of New Peoples Acquisition."

Two of the three visibly flinch back, though the armor hides any other reactions. 

The leader doesn’t. The air around him hums as he projects some kind of invisible magical shields from his armor. Perhaps an instinctive response to the threat. 

After the fire, a quiet moment. Each individual considering whether this is worth it.

The leader walks forward, with the sound of metal clinking. 

“Well then.” For a moment he sounds almost relieved. Looks back to the other two, before turning back.  

“Accept your apology for not checking in with us. Apologize to you for acting rash before we knew who it was we’re dealing with. Clearly not just some random on the street, clearly don’t need protection. Seems fair to say we both leave each other alone.”

"I'm a little mad about the damaged wood, those trees died for nothing now."

Hopefully this will come off suitably Elfily. It's also true.

"...But yes, it seems fair to say we both leave each other alone. The past is gone, and the future will have peace. I'm glad we could meet without violence. The institute of truces is a very good one."

Agreed! Especially truces with mysterious spirits who can afford to burn that kind of fire spell as a show of force.