KHD-1 is a boss enemy that you can fight during a Wrathborn hunt in Season of the Hunt. You will need a fully charged Crypolith Lure that you can get from The Crow on the Tangled Shore. You will first need to charge your lure by playing Crucible, Strikes, or Gambit, then right-click on the Crypolith lure in your Quests tab.
Place the KHD-1 Prey Mod in the Prey Mod slot, and then place whatever additional mods you have access to and want to use in the other slots. If you have none, just place empty mods in there. These mods will dictate certain aspects of the loot that drops when you kill HKD-1, so play close attention to them.
Now, check your map on the Tangled Shore and you will see a new icon of the location of a Crypolith that will start the Hunt. Go there and walk up to the Cryptolith and activate the Lure.
A large Fallen Servitor will appear, and you will need to take it out as quickly as possible. From time to time, you will notice a circle of green energy on the ground. Standing on this will give you a nice damage buff.
Just before they die, the Servitor will teleport away, and you will need to follow them. They will leave a trail of green energy on the ground, tracing a route to a small podium you will need to interact with to move into the next part of the hunt.
You will be teleported to a tunnel that leads to an area called The Boil and will find another Cryptolith inside. Interact with it to get enemies to spawn, including the massive Shank, HKD-1.
HKD-1 will be protected by a shield, and you will need to take out the Captains that spawn in. This will cause a circle of green energy to appear on the ground, and standing in it will get you a buff that will break the shield and allow you to damage the massive Shank.
When it dies, HKD-1 will drop Chest armor that is affected by whatever mods you loaded into the lure at the start of the Hunt.