Human clown performer at the Colosseum of Ashes, an interplanar fighting arena. Has an inflated ego and violent tendencies.

“I am not related to King Taron by blood, but he always treated me as a member of his family. I was a performer at his court, but my true role was to spy on the nobles I entertained. That is my purpose here as well.” - Deathmatch at the Colosseum of Ashes (RPA-SQ1)

Started as a performer in King Taron's court. Ended up at the Colosseum of Ashes. Often uses a trick sword in the theatrics in the colosseum.

Kalso displays narcissistic tendencies and hates to be outshone;

You hide behind Kalso as the children throw stones. One hits the clown square in the face. The audience laughs as blood gushes from his nose. Kalso is not amused. Without a word, he slaps the stone-thrower across the face. The other children scatter, fearful of a similar reprisal, and the audience boos Kalso’s maliciousness. He shoots you a furious look. In a huff, he marches from the arena. - Tome of Encounters (RPA-SQ1)

The entry on Kalso in a ledger found in Sylvian's private viewing area further iterates this:

Human entertainer from Ulos. Former court jester and known agent of King Taron from the Kingdom of Nalos. His performances continue to attract large crowds. With an artistic disposition, Kalso requires constant flattery and reassurances. If he refuses to perform, Colosseum administrators should attempt to appeal to his oversized ego before doling out punishment. When a performance fails to meet his expectations, he is a danger to himself and others. - Deathmatch at the Colosseum of Ashes (RPA-SQ1)

Kalso is the main entertainer at the Colosseum of Ashes;

You notice a poster bearing the image of a man in all black wearing red and white makeup. “The Great Kalso,” the poster reads, and in smaller print, it lists the days and times of his appearances. You discover the very same entertainer making his way through the crowd. A large group of children follow him through the aisles and laugh as he plays tricks on members of the audience. - Deathmatch at the Colosseum of Ashes (RPA-SQ1)

He has been seen to enter the arena for especially elaborate performances;

Dozens of children pour into the arena when the iron gates open. They are clothed in rags and carry buckets filled with stones. They all have strips of green cloth tied around their arms or legs. Following close behind them is a man all in black. He wears red and white makeup like a clown and tosses hard candy in the air by the fistfuls, which his child army dutifully collects. In his other arm, he carries an enormous papier-mâché head. It appears to be the head of a Troll. The audience cheers when they see him.

“Kal-so! Kal-so! Kal-so!” they chant. - Tome of Encounters (RPA-SQ1)

• Join the act and be bombarded by stones the children though, but earn the gold Kalso leaves for you.
• Join the act and run behind Kalso so the stones are hurled at him.
• Refuse to cooperate and suffer by way of your collar.

His four attendants lower the throne to the ground and begin assembling an enormous Dragon marionette. It is made from little more than parchment, woven fabric, and polished wood, but it takes all four of them to operate. They swing it over Kalso, who ducks, and the crowd gasps approvingly. Then the clown thrusts a wooden sword into the air and the fake Dragon seems to stumble backward, pulled by his puppeteers. The crowd cheers.

Kalso bows his head to you and offers you his sword, but then whispers harshly under his breath, “Take this, and then do as you’re told.” - Tome of Encounters (RPA-SQ1)

• Play along, and though singed receive gold from the audience for the entertaining act.
• Refuse to cooperate and suffer by combined shocks from your collar and surprise flame from the Dragon marionette.
• Scare off the puppeteers and score another point in your favor.

He stands on his horse, and then flips over backward, landing on his feet. The crowd hoots and hollers, again chanting his name.

He points his wooden sword at you, as if offering a challenge. The audience laughs. - Tome of Encounters (RPA-SQ1)

• Be at the mercy of Kalso's wooden sword, whacked multiple times.
• Outperform the performer with a wild dance that completely upstages the clown.