Plaguebian was created by his humble, yet bored and needy goddess to worship her in every move he makes. As the plebeian he is, his goddess never lets him forget the need to grovel before her awesome puissance and watch out for his Guild Name homies.
In the spirit of his lowly calling, Plaguebian would never willingly step into a duel with his fellow heroes; instead, he wastes his meager resources in spreading sappy messages of love to his rivals like a diabetes-inducing plague and sympathizing with the monsters he would end up killing anyway.
Feel free to look down your nose at little Plaguebian. It will put a smile on his borderline-sadist goddess.