While you are killing what needs to be killed, here's the dialogue:
Exarch Hataaru says: Keep them engaged. The defense ward is drawing so much power - I can't maintain it for long.
Exarch Hataaru says: It's working! It's...not stable. But it's working.
Exarch Hataaru says: This new structure is able to tap into a surprising amount of power.
Exarch Hataaru says: Keep the Shadowmoon at bay. What is causing this madness?
Exarch Hataaru says: Defend the ridgeline. Let them come to us.
Once you've killed enough to complete the quest:
Shadowmoon Dark Zealot says: Pull back! We must find Ner'zhul his sacrifices elsewhere.
And once you've turned in the quest, an elite fungal giant comes to say hello! Don't worry, there's help there to kill it.
Exarch Hataaru says: Stop that thing! Bring it down!
Exarch Naielle says: What is going on here? The entire mushroom forest is riled up.
Exarch Hataaru says: Stay in your swamp, Rangari. I will handle this.
Exarch Naielle says: Did you sink resonance crystals in the ground again? You're driving the creatures of the earth berserk!
Exarch Naielle says: When will you learn that this world is nothing like Argus?
If you speak with Exarch Naielle, it is as follows:
<The two Exarchs are in the middle of a heated argument.>
Exarch Hataaru focuses too much on what we lost. I keep trying to tell him - it would be folly to turn this world into a second Argus, even if we had the power. Draenor is unique, and we should build our technology to suit this new world. Not the other way around!
He seems willing to listen to you. Maybe you can talk some sense into him.
If you speak with Exarch Hataaru, it is as follows:
<The two Exarchs are in the middle of a heated argument.>
Thank you for all your help, <Name>. Apparently my devices have riled up the local flora - not to mention my fellow Exarch.
It is no matter. I will do whatever it takes to defend our people and rebuild what we lost...the occasional but is to be expected. Surely you agree!
The next quest is The Exarch Council. Mount up or Maraad will leave you behind!