Should I help O DIMM or Olgierd?
Either end has the same outcome in that respect, so it's a matter of choosing a lesser evil when deciding which one to let walk free. But if you pity Olgierd, letting him die mercifully allows him to escape his grief and ensures he won't continue harming innocents.
In this mission, Geralt of Rivia must decide whether or not to save Olgierd von Everec from Gaunter O'Dimm. The choice he makes results in the apparent death of one or the banishing of the other.
Type of Villain
Olgierd von Everec is the titular villainous deuteragonist of Witcher 3: Hearts of Stone. Olgierd is an arrogant Redanian noble, who wanted to marry Iris but their parents didn't allow for this due to his bandit lifestyle and poverty. They arranged marriage with an exotic prince instead.
If he chooses this reward, O'Dimm will give Geralt the 'Horn of Plenty,' providing the witcher an endless supply of food. Each time Geralt pulls from this cornucopia of sustenance, he will receive 40 vitality and 25 vitality regeneration during combat for a five-second duration.
If you want to never go hungry again you receive a Horn of Plenty which basically acts like unlimited food. You can ask for an endless bottle of vodka and never buy alcohol for your potions again. If you want to be rich, Gaunter gives you a small amount of gold (5000). If you ask for nothing, he just disappears.
Through questioning, O'Dimm told Geralt that he was neither demon nor djinn and that it was not his fault that the negative intentions of his clients caused them to suffer, explaining to Geralt that he gave people exactly what they wished for.
Hearts Of Stone was The Witcher 3: Wild Hunt's first expansion and features two different endings.
After many years, they finally meet in an inn called Rome, but Twardowski uses his magic to escape the devil and live on the Moon. Another possible inspiration for O'Dimm is Stephen King's Needful Things. Gaunter O'Dimm's acronym is G.O.D.
Gaunter O'Dimm, also known as Master Mirror and Man of Glass, has been known to bargain with men for their souls, granting them unbelievably powerful wishes in exchange for grim and horrifying offerings.
Gaunter O'Dimm is the perfect villain originating from a game worthy of its numerous accolades: The Witcher 3: Wild Hunt. With complex, memorable characters and an in-depth storyline, as well as immersive atmospheres in a magically infused world.
What happens if you don't take the rose from Iris?
Leave the rose
If Geralt decides to let Iris keep the rose, the dog and cat will be resigned to their fate to watch over her, hoping another in the future will free them. Iris will go back into her slumber, and Geralt leaves through the portal back into the real world.
The Toussaint Knight's steel sword is, without a doubt, the best steel sword in witcher 3. It is easily the best of the best, having +300 armor-piercing, absolutely decimating foes it encounters in its way. This sword deals 745-911 damage, which is insane.

Turns out Ciri isn't the only being in The Witcher 3 that can play time and space like a fiddle. Gaunter O'Dimm does it regularly and even casually whenever he fancies. For all anyone can know, he could well be more powerful than Ciri. His grasp on his powers is certainly more elegant.
10 Strongest: The Iris, Olgierd's Sword From The Witcher 3
It's an insanely useful blade that flashes red after striking the enemy 2-4 times with a light attack. If Geralt executes a strong attack when it flashes, he'll do some insane damage at the cost of a bit of his health.
Roughly translated it says; You think you have won from me.
The Witcher 3: Gaunter O'Dimm's Minor Role in the Blood and Wine Expansion Explained. Gaunter O'Dimm may have made his mark in The Witcher 3's Hearts of Stone expansion, but he also plays a minor role in the Blood and Wine DLC. The Blood and Wine DLC in The Witcher 3: Wild Hunt was the final expansion added to the game ...
As will all the players know, Geralt spends a significant part of the base game looking for Ciri - only to find that she's on the Isle of Mists.
Not only is he not the most powerful being out there, he's not even the most powerful being you meet.
Shani. Shani is a romance option in the Hearts of Stone DLC. Shani only appears in this expansion, and outside of Yennefer and Triss, she offers the most in-depth romance available in The Witcher 3. Romancing Shani has no impact on the rest of the game and the other romance options that Geralt can pursue.
Once players begin the Hearts of Stone DLC, they are reintroduced to Gaunter O'Dimm through a magical pact that the character seals with a sigil burned into Geralt's face. Beyond that, it is revealed that the mysterious character has made a deal with Olgierd von Everec, the immortal central character of the DLC.
What is the best Witcher 3 ending?
One of the best endings in Witcher 3 is to get Ciri to live and make her a witcher.
The Devil of the Witcher World
To put it simply, Gaunter O'Dimm is the Devil, but not necessarily a Christian one. If you choose the Help Olgierd in the end, you also get to see Gaunter's face changing to his real appearance.
Nilfgaard can be considered as the best outcome of the war. With Radovid being a murderous tyrant and Dijkstra a morally questionable choice, it is easier to think Nilfgaard winning and restoring Temeria is better. It is necessary for Nilfgaard to win to get the Empress Ciri ending.
In short, I believe that O'Dimm isn't just a creature that collects souls but outright consumes them. They're his sustenance, in a more literal way than the metaphorical sense of deals and pacts “sustaining” him in his immortality—AKA keeping him entertained.
"Gaunter O'dim" is an anagram of "guitar demon".