Duke Hydraxis is a water elemental located in The Heart of Azeroth, where he is a shaman champion. He is the leader of the Hydraxian Waterlords, and is a servant of Neptulon the Tidehunter.
Cataclysm, Hydraxis was a quest giver located on an island northeast of the Ravencrest Monument in Azshara.
Duke Hydraxis revealed in his quests that the "pure" Elementals of Water are seeking to do battle against the other elements, and were willing to let mortals prove themselves to be worthy of fighting one of their grandest enemies,
Ragnaros the Firelord and his servants in the Molten Core.
Legion This section concerns content related to . Legion
Hydraxis is sent by
Neptulon to join the Earthen Ring at the Heart of Azeroth.
He participated in the
Battle for the Exodar battling against High General Rakeesh, along with Stormcaller Mylra and Stormbeak.
Battle for Azeroth
Battle for Azeroth.
Hydraxis is back in Azshara, on the northern-eastern point of the Horde logo-shaped land in the
Bay of Storms. He mentions that Azerite has thrown the elemental planes into chaos.
Hydraxis later appeared alongside
Neptulon and Champion Aquaclease to do battle with the forces of Queen Azshara in Nazjatar.
Duke Hydraxis before
in his original spot. Legion
Quotes This section concerns content related to . Legion
Lord Neptulon has sent me to aid the Earthen Ring in the defense of Azeroth. I have been commanded to serve the Farseer of the Earthen Ring with the same loyalty I give to the Lord of Tides. I will fulfill this duty until the Burning Legion is driven from this world and the future of Azeroth is secured. I am yours to command, Farseer. 
The Heart of Azeroth
I am yours to command, Farseer.
I am at your call.
I am ready.
I live to serve.
The battlefield awaits.
What are your orders?
Yet little time.
What is the point of this?
You are wasting time!
My patience wears thin!
I am not amused!
Our fate is in your hands.
Fight with honor.
As you wish.
[50WQ] The Lords of Water Greetings mortal. The naga have committed a grand crime against the power of my master, Neptulon.
The magic of the Tidestone is the magic of titans. Even now, that ancient power holds him at bay just as it holds back the sea. However, it cannot hold back his justice.
Will you join me in quelling these naga for their defiance of the great Neptulon?
I am ready.
Come, little Champion, and let us drown our enemies in the tides of justice!
Drown in the tides of vengeance!
Let the waves consume you!
Pathetic. Nothing more than a ripple!
Neptulon reigns upon you!
Splashing! Water you waiting for? Face me!
Combat ally This section concerns content related to . Legion
Let the elements flow through you!
The primal waters cleanse all! The tides are eternal!