KarinsDad has the right of it. Having defeated a rogue demi-god last week, the players are most likely to turn their attention to some major tasks that were on the 'nearly as important' list. One is to reseal the prison of dread Tharizdun before it gets any shakier. The other is to hunt down three extremely powerful Yugoloth assassins called the Khrel Hr'dad who are running loose on the Prime.
I could have them enter directly into single combat with each one, but I'd rather they have to fight their way through their demonic armies, first. Understand that the Yugoloths are CR28-33, so the players will need to wade their way through some advanced Balors, Mariliths and a few swarms of dretches at the very least. Having the Yugoloth simply turtle-up and order his minions to attack allows the players to flex some muscle and makes him the final boss, not just someone they bypass all the other monsters to get to.