D&D 5E Revenge is best served cold (looking for inspiration)

[Inglorin]

Hiho,

my adventurers sent Acererak into timeout. After his 1d10 days of forced rest he will have something to say about this. I am looking for inspirations for his revenge. How could he make their live into hell? He WILL try to split the party up. He will have no inhibitions to fight dirty. They are going to suffer. But how? What are your best ideas?

TIA.

 

[DND_Reborn]

Can you tell us more about the party? Classes, levels, etc.?

 

[Benjamin Olson]

Have him join their group in disguise and adventure along with them then backstab them all and make off with their treasure.

 

[Seramus]

Have him offer souls to some Night Hags. Have them follow the party around and give them nightmares.

Warning: Your players will hate you.

 

[aco175]

Where/how did the party defeat him. Was it in a published adventure? Either way, the long set-up is best with revenge spread over a few levels. Another idea is that he does not want to tangle with the PCs again and would just assume to live without meeting them again. Sending minions works well as well.

 

[Cadence]

Keyser Soze supposedly did some things if you've seen the Usual Suspects. If you haven't, you really should first and then you can Google his name and 'owed them' for the list. It's decidedly not a movie related to D&D, but it would work for a party whose members had back stories.

 

[Benjamin Olson]

Have him offer souls to some Night Hags. Have them follow the party around and give them nightmares.

Warning: Your players will hate you.

He could also just cut out the middlemen and use the Dream spell on them every night with the nightmare end.

Naturally he should be taunting them to visit another of his funhouse dungeons because those are his whole deal.

 

[Arvok]

1. Acererak kidnaps a couple of babies (probably through the use of henchmen/servants), making sure one of them is somewhere near the PCs.
2. Acererak gets information to the PCs (maybe through a henchmen or by letting someone follow the kidnappers) that the baby (the only one the PCs know of) is being held in a dungeon and will be sacrificed in a ritual (to summon an evil god or something).
3. Just before the PCs bust into the final room where Acererak's minions are performing the ritual (to sacrifice the other baby), the Lich casts true polymorph on the baby the PCs know about and turns it into a creature that fits the setting and is a threat to the PCs (but not too powerful).
4. The PCs kill the 'monster', at which time transforms into a dead baby; damage carries over and baby is dead (how many hp can an infant have?).
5. If you want to be extra sure the baby stays dead, Acererak can be observing through a peephole in an adjoining secret room to counterspell any attempts to revivify the baby.
6. The PCs emerge from the dungeon and seek out a means to raise the infant from the dead, but Acererak and/or his minions have already prepared the environment so that the NPC villagers/religious elders see the PCs as murderers (maybe just after the PCs set off to rescue the baby one of Acererak's minions shows up warning the NPCs that the heroes are actually villains working to ensure the ritual takes place).
7. Acererak continues to manipulate things so that the PCs are hunted as villains.

You will probably need to change things up for your particular setting/situation, but I hope this can serve as some inspiration.