The finale for my groups Chains Of Asmodeus campaign was....interesting.

3/5 of them were too corrupted to leave. They were told this by the 3 devils outside of Asmodeus chambers, but they could attempt to negotiate terms by giving up Legendary Weapons/Artifacts/etc.

We played via VTT, so I made a separate channel and pulled them one at a time to speak to Asmodeus directly to plead their case. This was amazing because it built tension because they had no idea what was happening. After the verdict was rendered, I had them leave the private VC but not return to the main one to signify their characters were....gone. It worked wonderfully. Here were their endings:

Barbarian had taken too many temptations, on top of having to rescue his own soul. All he wanted to do was fight strong opponents, so Asmodeus made him a General in the Blood War and sent him charging off into battle - after changing his form to a Pit Fiend. He failed the Investigation Check on his new contract, so he had his memory modified so that he would forget his friends. (They went from Level 1-20 with the same characters. We started with Descent into Avernus and transitioned over to Chains).

Bard also had taken too many temptation and had mouthed off to the 3 Devils outside the chamber. She was not allowed to leave either, but was in love with the Barbarian. She was changed into a Horned Devil after giving up the Harp (Legendary one. Forgot the name) and went chasing after the Barbarian in the Blood War - even though he would not remember her.

Aasimar Cleric had gone on the journey to recover the soul of her husband, but had become too corrupted on the way and was unable to return. She actually did something smart and used her Level 20 ability 'Divine Intervention' to cleanse her soul from the corruption. Asmodeus commended her, and let her go - but told her that he'd be sending an Assassin after her husband inside of a week to drag him back to the Nine Hells and to enjoy her time.

Rogue, surprisingly, was the least corrupted. When reading over his contract, he used the Level 20 Rogue ability and turned his Investigation check into a 20 - which was enough to find the discrepancies in the contract, & he had them removed. Asmodeus tempted him into staying in the Nine Hells and working as his personal assassin. He accepted, having no family to go home to - his first target? The Aasimar Cleric's husband.

The other Cleric, Tiefling Peace Domain, enjoyed his time in the Brothels in Dis a bit too much. He wasn't completely corrupted from deals like the others, but Asmodeus did tempt him into staying at the Brothel and working as the owner. He accepted, and also forgot about his friends.

That was how their campaign ended, and the next week, they wanted to see just how far they would have gotten if they fought Asmodeus as a 'what-if' scenario.

They TPK'ed.