Darksiders Genesis

This walkthrough comes straight from steam wich can be found here.
https://steamcommunity.com/sharedfiles/filedetails/?id=19665...
Credits to Omega Ridley

Defeat less than 5 hounds before killing the Houndmaster in The Horde.

Notes: Now this one is tricky, probably one of the most difficult achievements in this game. Fortunately, there’s a way to make it completely trivial. First things first tho, you’ll want to play as Strife and not War, as the latter has a lot of range with his sword attacks, and you’ll want to focus your damage in a single spot: The Houndmaster’s face. You should also avoid equipping any Creature Cores that reflect the damage you receive towards foes.

Follow the alternate path into the Hoard found south of the main gate and make your way through the Growth bomb puzzle without killing any Hounds. Be swift, as they’ll start swarming you if you are too slow, making it difficult to progress.

With the puzzle behind you, enter the Houndmaster’s room and trigger the cutscene. As he attacks you, stay at a safe distance and unload your regular ammo into his face. Avoid Charged or Static Shots, as those have a nasty habit of dealing collateral damage and you have to keep the dogs alive at all cost. Keep it up until the Houndmaster is defeated.

If you’re having trouble, this achievement can be cheesed: As the fight starts, lead the Houndmaster to the northwestern section of the room, and stay slightly behind this crate.

The boss will stop moving and so will his Hounds, allowing you to damage him from afar without any risk of retaliation or dogs getting in the way.

In this video guide I will show you how to defeat less then 5 hounds before killing the Houndmaster in The Horde. So to get to this area there will be a door on the top right side of the map. Just follow the right side and climb up some structures until you go through a door.

Once inside there will be hounds in there. These also count to the achievement. So make sure you don't kill any here. What you need to do is to grab the exploding ball and throw it at the switch that is in the room next to the ball. After that a gate will open, you will need to use Strife's ability to open up the portals. Once you get that side open you will need to head to the right and up. There will be another portal to open up. Just stand on the cages to open it up safely. Now go through this end of the portal to go quickly grab the exploding ball again and go through the portal to destroy the rock. If the gate is not open when you go through the portal, just hit the switch.

Now for the boss fight. Once the fight starts you want to run around for a bit and try to get the hounds rounded up and away from where you will stand. There is a spot behind some cages in a corner where they can not hit you. Just stand there and peak out until you see the Houndmaster come around. Now all you need to do is try to get him in a spot away from the majority of the hounds. Once you do just use Strife and shoot him until he is dead. It is no big deal if you happen to kill a few hounds. Just pay attention to the side mission tracker in the menu. If you kill too many you will have to restart the whole mission. Once he dies before the hounds do the achievement will pop.

This is an easier way to do it:


NOTE: I take no credit for this video.