Abyssal Architect (6/15/20)

Your party is in the Battle Grove. You have been spotted by 2 hell hounds. They have both been hit by ShitBoy's Eldritch blasts in their pursuit and you have caught the attention of the Avatar of Tharizdun. Roll initiative!
The avatar will either teleport to the prison or die and make the prison Avatar Stronger. Its death is accompanied by a massive explosion. The party can regroup from there and figure out their next move.
If they wait a day or two before pursuing the second avatar, there will be twice as many Plague demons infesting the prison as before. Encounters on the way to The Prison?? Cabin with portraits if they bed down for the night
A great Elk is seen watching the party from a distance. It almost looks as if the elk is wearing a crown made of twigs and vines.
A tribe of Firbolg are seen disappearing into a tree. They look sad and hurried to leave.
You find three bears eating the corpse of a blonde female. They revert to Human form once they die and their recently ransacked cottage is nearby.
The third one is in the Feywild trying to attack the Summer Queen.
If he gets to Ukko, they will be teleported to the abyss. and will have to fight their way out.
The party can get some down time. After a few days the Avatar will reemerge on the material plane with a Sibriex pouring demons into the material plane.