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I'm running a 5th ed campaign that's getting close to finishing out a big story arc where the PCs are hunting down a vampire lord trying to take over the city they're based in. The group should be level 15 once they get into the big showdown with the vampire.
My players are pretty clever and I'm hoping to present them with a challenging fight to make the Big Bad in question memorable. But I'm concerned that the base vampire stats won't be a huge challenge. I'm designing the encounter to make for some fun along the way, but I'm hoping to make the vampire himself stand out. Storyline wise, he's one of the most powerful vampires in the campaign world, so I hope to make him seem special.
Toward that end, I've rolled up a level 15 elf sorcerer and given him the vampire powers on top of his stats. I can't get a sense if this is too much or too little, though, and I was hoping someone can give some insight on this, particularly if you've tried this approach yourself, with Fifth Edition.
Also, I may be blind; if there's a place in the DMG that talks about this particularly, I've missed it (and my DMG is currently in a box because I just moved).