Beastmaster And His Almighty System

Wang Yan had traveled through the Familiar World, but due to his limited talent, he could only contract with the lowest grade of spirit beasts.
Fortunately, he had the privilege of being a traveler, and had awakened the fair trade system.
As long as it was something of his own, he could trade with the system?
A bold idea suddenly surfaced in Wang Yan's mind: "System, trade for hemorrhoids!"
System: [Exchange successful, obtained 1 point!]
Hearing the system notification, Wang Yan was ecstatic. It seemed like he had found a loophole in the system!
Poison from the elixir? Trade!
The harmful energy within the alternate dimension? Trade!
The impurities within his body? Exchange!
Little snake transforming into a true dragon, chicken transforming into a phoenix!
With the System in hand, I am invincible!