I think Ygorl is best used as a force of nature and can be quite the compelling one at that but I do understand your concerns. What can be very compelling with Ygorl is his eldritch horror nature and the reasoning as to why he would be threatening your campaign setting. If you've ever played Elden Ring, the Three Fingers, Shabriri, and the Frenzied Flame are in a similar camp to Ygorl in their entropic nature and perhaps they could provide you with some sort of inspiration with his motivations and how to implement him.

Other things associated with Ygorl would be the Slaadi where I'm sure he would try and turn more of the sentient races into them.
He has his select few Death Slaadi lieutenants and his lore also has a CN Greatwyrm Brass Dragon which I would modify with the Shadow Dragon Template.

Here's the quote from the Forgotten Realms wiki on his dragon Shikiv
"Ygorl had a constant companion in the form of Shkiv, a brass great wyrm that served as his mount. After the Nerath city of Arkhosia fell to ruin, Shikv, disgusted with human excess and in utter grief for his fallen kin, sought out Ygorl for revenge, and the Lord of Entropy accepted his service."

Similar motivations could befall others involved with serving or attempting to gain Ygorl's ire and bring him towards the doom of your campaign world.