I’m having my party fight my first BBEG in about 2 days and I wanted some help building the BBEG or BG to shorten it, the BG is a cult leader that’s obsessed with otherworldly travel and beings, the party should only be about 4-5 or 6th level by the time they get to him, so I basically wanted to give him the evil mage stat block, but the cult leader helps the party fight through an ancient ruin and gets on their good side, just to be possessed in the end by an ancient spirit or demon etc... I have a stat block for him before he changes, but can someone build or help build me a possession type monster?
I never played with posession in D&D, but I would probably rule that he keeps all his physical ability scores while his mental ability scores and skills are replaced with those of the demon.
And probably resistance against all damage except psychic would be appropriate. That equals a Barbarian's resistance during rage and should represent that the demon does not really care about the body it possessed.
As template for the demon I would probably use a Night Hag (Coven), without the coven restrictions. So, using an Archmage for the cult leader and a Night Hag for the demon something like this might work:
HP: 99, AC: 15, Resistance to all but psychic damage.
If the party reduces him to 0 HP, have the demon emerge at full strength (using the Night Hag stats without changes) for a phase 2. This would be equivalent to fighting a shapeshifter / druid and make sure the BBEG is around for more than a single combat turn.
If you realize the group is already exhausted after phase 1, let them fight for maybe a round or two before the cultist regains his conscience a casts a quick Tiny Hut for the party to retreat to while the annoyed demon escapes to find a new host.
I wasn’t sure what you were really asking for, but I like the first response you got. Those were great ideas. What I got from the OP was cult leader who was into otherworldly beings and possession, and you needed to build him from scratch. I hadn’t thought about demon summoning and possession. Shows how little I think of such things. But it makes sense that such a BG would give himself a battle form by inviting something to possess him, and a demon certainly fits the bill.
So that’s one way you can run it. Another way I initially was thinking was more like the Ghost possession ability, that maybe either he can possess enemies himself, or conjure ghosts that can do it for him. Mechanically, he has an item or spell that summons spirits and they act as minions in the battle, but focus on their possession feature. Ghosts are CR4, so unless you nerf them (maybe as freshly summoned, or involuntarily summoned, they aren’t as strong) you probably can’t justify more than 1 on top of your BG for a 6th level party.
If he’s possessing them himself, maybe if he uses an action to touch a gemstone to the PCs, he can possess their souls and control them for a set period.
The easy way of doing this is a spellcasting monster with access to Magic Jar. That means the mage's stat block isn't very relevant because you're using the abilities of the possessing monster (the mage's body is mostly a hit point buffer), but since Magic Jar requires at least an 11th level caster, that won't much change anything. A spirit naga seems like a good base encounter.
I’m having my party fight my first BBEG in about 2 days and I wanted some help building the BBEG or BG to shorten it, the BG is a cult leader that’s obsessed with otherworldly travel and beings, the party should only be about 4-5 or 6th level by the time they get to him, so I basically wanted to give him the evil mage stat block, but the cult leader helps the party fight through an ancient ruin and gets on their good side, just to be possessed in the end by an ancient spirit or demon etc... I have a stat block for him before he changes, but can someone build or help build me a possession type monster?
From the crypt...
I never played with posession in D&D, but I would probably rule that he keeps all his physical ability scores while his mental ability scores and skills are replaced with those of the demon.
And probably resistance against all damage except psychic would be appropriate. That equals a Barbarian's resistance during rage and should represent that the demon does not really care about the body it possessed.
As template for the demon I would probably use a Night Hag (Coven), without the coven restrictions. So, using an Archmage for the cult leader and a Night Hag for the demon something like this might work:
HP: 99, AC: 15, Resistance to all but psychic damage.
Str 10, Dex 14, Con 12
Int 16, Wis 14, Cha 16
Deception +7, Insight +6, Perception +6, Stealth +6
Spells and Actions from the Night Hag:
https://www.dndbeyond.com/monsters?filter-search=&filter-type=9&page=3&sort=cr
If the party reduces him to 0 HP, have the demon emerge at full strength (using the Night Hag stats without changes) for a phase 2. This would be equivalent to fighting a shapeshifter / druid and make sure the BBEG is around for more than a single combat turn.
If you realize the group is already exhausted after phase 1, let them fight for maybe a round or two before the cultist regains his conscience a casts a quick Tiny Hut for the party to retreat to while the annoyed demon escapes to find a new host.
I wasn’t sure what you were really asking for, but I like the first response you got. Those were great ideas. What I got from the OP was cult leader who was into otherworldly beings and possession, and you needed to build him from scratch. I hadn’t thought about demon summoning and possession. Shows how little I think of such things. But it makes sense that such a BG would give himself a battle form by inviting something to possess him, and a demon certainly fits the bill.
So that’s one way you can run it. Another way I initially was thinking was more like the Ghost possession ability, that maybe either he can possess enemies himself, or conjure ghosts that can do it for him. Mechanically, he has an item or spell that summons spirits and they act as minions in the battle, but focus on their possession feature. Ghosts are CR4, so unless you nerf them (maybe as freshly summoned, or involuntarily summoned, they aren’t as strong) you probably can’t justify more than 1 on top of your BG for a 6th level party.
If he’s possessing them himself, maybe if he uses an action to touch a gemstone to the PCs, he can possess their souls and control them for a set period.
The easy way of doing this is a spellcasting monster with access to Magic Jar. That means the mage's stat block isn't very relevant because you're using the abilities of the possessing monster (the mage's body is mostly a hit point buffer), but since Magic Jar requires at least an 11th level caster, that won't much change anything. A spirit naga seems like a good base encounter.