Design Help -- Mindflayer Vampire Boss

[tortor]

Looking to put together a strong boss monster for a party of Undead slaying maniacs (A paladin, A ranger with Undead favored enemies, a "don't move" style pole arm fighter and a ranged dps rogue)

I thematically settled on a mindflayer vampire but I am uncertain of how it would be best executed...

For lack of better words, I'm hoping for a stat block and maybe a short blurb on how you'd run the creature. The party should be at least level 13 by the time they fight this thing.

[Specter]

Vampire sounds redundant here. I mean, vampires suck blood, mind flayers suck brains. Sucking both seems like too much hard work. Maybe a mind flayer revenant, or lich, or death knight?

Anyway... legendary actions, like moving without op. attacks and making an extra attack are a must for one-boss fights. Then at least some 200hp to give some challenge, along with regeneration. That's a good start.

[Idkwhatmyscreen]

A Vampire Mindflayer would be no fool. Vampires tend to get drawn into their own Immortally, seeing themselves as perfect undying Demigods, who have a right to drink the blood of whatever they choose. A Mindflayer comes from a realm of madness, where beings of power beyond mortal contemplation just chill, with one breath they could destroy the world if they so choose, the only reason they don't is the world is too small for them notice. The Mindflayer knows it is nothing.

A Vampire Mindflayer would desire its immortal destiny, but simply know too much about the real order of things that instead of living it up in a castle, it would keep a lair located deep in the underdark. Death is inevitable for the Vampire Mindflayer, it is not an Elder God, at least not yet anyway. Only they are truly beyond death. The 10,000 years a vampire can expect to live before a group of lucky adventurers take it out is pocket change in the grand order of things.

So how does one become an Elder God, a being of power so great, that not even you can hurt yourself? Good question this is what your Squid faced bloodsucker is looking into. Go ahead and give him 25% of the knowledge that he needs to know for the ritual to become an Ancient One. Next give him a good mix of undead and living servants whose only goal is digging up the ancient knowledge that he lacks. They should be doing more than just raiding libraries. They should be breaking into tombs lost to time, other planes of existence, and enslaving creatures of lore to their masters bidding. Each target they hit has X% of the knowledge that the Mindflayer needs. If left unopposed they will get all of it. They only get a fraction if the party stops them.

Once the Mindflayer has all the information that he needs, he will begin working on the ritual proper. If the party has not pieced together what he is up to or where he might be hiding, you will need to have him collect massive number of ritual components. (so, they have a trail to follow to his lair) From there you have a big climatic fight. Know you should not have the Ritual make the Mindflayer Cthulhu at Lv. 13, but rather the ritual would give the Mindflayer the power it needs to be a lv. 20 universe ending threat.


I would give mechanical ideas, but I am away from the books