Like the boss before him - and many throughout Demon's Souls - the Dirty Colossus is extremely weak to fire. He also only has four different sets of attacks he can use, so he is easily countered and defeated.

One important thing to note, is to try not to break his wooden arm. If you do, he will release flies that randomly attack you throughout the fight.

Demon's Souls - How to beat Dirty Colossus

The first attack Dirty Colossus has is his ranged fly barrage. You can spam side roll to easily dodge this attack. If you do get hit by the fly barrage,they will stick to you and do massive damage over time. Run into the nearest torch and it will burn them away

Secondly, he has a forward punch that does a decent amount of damage
Third, he has a three hit combo where he swings around him and knocks back anyone who gets hit. Stay away from him or behind him to dodge this attack

Lastly, he has an explosion where he curls inward and gathers flies around him. He then bursts and does damage in an area around him. Be sure to roll away the second you see the animation

Enter the boss fog and use Turpentine to buff your weapon with extra fire damage or equip the Dragon Long Sword +1 if you picked it up in World 2-2.

The best way to fight the Dirty Colossus is to stay behind him constantly and attack his back. Be sure to reposition as he turns to face you. Your fire damage should melt away his health in a few R1 combos and the Dirty Colossus should be no more.



Dirty Colossus Cheese Strategy
The quickest way to defeat Dirty Colossus is to use Firestorm on him. You can learn Firestorm from Yuria after defeating Dragon God in World 2-3. Run up behind him and cast Firestorm directly on top of him. This attack spreads out and hits multiple times, so it's extremely damaging and can defeat him in one cast if the full Firestorm lands.

The absolute easiest way to defeat the Dirty Colossus though, is from the entrance with either Soul Ray or any bow.

Hug the left side of the wall and use the wooden plank as cover. Peek out and attack, then immediately take cover behind the wood. Repeat this until the Dirty Colossus is dead.

This method can be sped up by using Hyper mode. Hyper mode can be achieved by equipping the Clever Rat's Ring and/or Morion Blade when you are below 30% HP to increase your attack power by up to 140%. You can find the Clever Rat's Ring outside the boss fog in World 3-1 in the middle of the ballista hallway. You can create the Morion Blade at Blacksmith Ed after defeating the Storm King in World 4-3.

Equip the ring, offhand the sword, and take enough damage to get to 30% health. An easy way to do this is to get poisoned on purpose on the way, then cure yourself by using Royal Lotus. You can equip the Magic Sword "Makoto" if you have it for an easy way to drain your health. You'll know you're at 30% when you see a rat icon below your stamina bar.

After defeating the Dirty Colossus, you will receive the Eroded Demon's Soul. This soul can be used to learn the spell Acid Cloud from Sage Freke.