Help me improve my BBEG!

[ciarannihill]

So my longer running game is coming to it's first major arc conclusion soon, my players are starting on the "war path" to siege a city that has been taken over by a usurping individual who is, in reality, a Rakshasa.

This Rakshasa, who is named Atikaya, has been performing experiments on some of the local populace, towns and monsters trying to combine them with various magical creature parts -- Medusa blood, Dragon scales, Flind hide etc. His method of acquiring these components was by infiltrating and taking a high position in the Cult of the Dragon Queen.

I plan on Atikaya being a 3-stage fight, with some extra minions.

The first stage being his adopted identity in the cult, a high priest of Tiamat who fights alongside several cultists and a dark paladin, when bloodied he will drop the façade and move to stage two.
The second stage being a Rakshasa with two legendary resistances and one legendary action to cast a spell or make a melee attack each round, the cultists will attack him and the party alike in this phase, but likely they will be mostly wiped out by this point, given the way the party fights. Upon being reduced to 1/3 HP he will attempt to flee to the safety of his laboratory where the party who likely chases him will find him fusing with the ultimate material he had acquired -- scales from Tiamat herself, granting him a new more powerful, but very unstable form, thus beginning the third phase.
The third phase is the one I'm having difficulty with, what powers and flaws should such a combination bring forth?
Obviously I can increase the HP/AC, but I'm thinking that he should have some Tiamat themed abilities. Frightful Presence is a sort of no brainer, but should he have a breath weapon? What damage type? How many legendary actions/resistances?


I'd like to be able to challenge them heavily without forcing a TPK, although if the dice fall that way that's what happens. There is, currently, a plan for a specific NPC who's village fell victim to the Medusa blood based concoction to assist them in the fight, although depending on their decisions leading up to the fight he may or may not appear.


Information about the party: It consists of 3 members, a Tabaxi (Revised) Beastmaster Ranger/Rogue multiclass, a Goliath Vengeance Paladin/Hexblade multiclass and a Half-Elf Grassland Druid. The Druid and Ranger are both level 8 and the Paladin is level 9, and by the time they hit this fight they will likely have leveled up 1 or 2 more times, depending on how they go about arriving at it.

Their most recent fights included a dungeon crawl that culminated with a fight with a Beholder and 2 Death's Kisses (with some NPC aid, mostly as distractions for the Death's Kisses attacks), followed up by an enraged Adult White Dragon after just a short rest (the dungeon was a massive contest between a huge number of adventurers and the dragon was made to go berserk and attacks the "after party"). They did get a bit lucky with die rolls, but the Paladin is kind of a monster against single targets.

I'd be super grateful for any thoughts this community might have for how to make this fight the most epic capstone I can make it for this arc/campaign.

[Harpier]

How much of his mind is still intact when the fusion takes place? (i.e, will he be blindly lashing out at anything he remembers to be an enemy, or will he still have enough wits about him to adapt to his new form and use actual tactics.) A big part of determining the abilities of the boss is answering that question.

-Multiple heads with their own attacks might help the boss keep pace with the party's damage output, maybe even with the same rules as the Hydra's if the fusion is still shifting. Maybe fluff a recharging breath weapon with multiple damage types involved as a sort of combination attack?

-I'd suggest regeneration, both due to the Tiamat statblock having it, and the idea of an unstable and shifting fusion, but that might not be what you want, and that might make the fight a lot longer than you anticipated.

-Will this fusion be able to fly? It won't be a factor if the lab is underground or indoors, but if it's somewhere sky-accessible, it will definitely amp up difficulty. Wouldn't recommend unless the melee attackers have some way to fly themselves, or the party can destroy his wings by aiming for them and beat him up when he falls. (Did that with a boss, worked pretty well, brought it down to range with the tradeoff of it being able to use it's own melee attacks effectively when it was downed.)

[ciarannihill]

How much of his mind is still intact when the fusion takes place? (i.e, will he be blindly lashing out at anything he remembers to be an enemy, or will he still have enough wits about him to adapt to his new form and use actual tactics.) A big part of determining the abilities of the boss is answering that question.
I feel like it is a moment of berserk rage, perhaps if he were to escape and have his transformation stabilize he would regain his full cognition, but due to the hasty nature of the action he loses himself in the moment. At least in my head I feel like having that occur sells why he hadn't simply transformed before being in danger: He hadn't worked out all the kinks and would prefer to minimize side effects if possible. given that it might be worthwhile to have him do something akin to the Barbarian's Reckless Attack thinking about it, not necessarily mechanically, but thematically where he's lashing out so aggressively that he ignores defense entirely.


-Multiple heads with their own attacks might help the boss keep pace with the party's damage output, maybe even with the same rules as the Hydra's if the fusion is still shifting. Maybe fluff a recharging breath weapon with multiple damage types involved as a sort of combination attack?
Sounds like a good way to get the breath weapon flavor and feel of Tiamat without getting insane with the power level, good note!


-I'd suggest regeneration, both due to the Tiamat statblock having it, and the idea of an unstable and shifting fusion, but that might not be what you want, and that might make the fight a lot longer than you anticipated.
That sounds like a perfect mechanical way to imply the nature of the transformation, A+. Will do. Might make it similar to the Troll's regen in that the damage type that Rakshasa's are vulnerable to (magical piercing damage from a good character) halts the regen for that turn.


-Will this fusion be able to fly? It won't be a factor if the lab is underground or indoors, but if it's somewhere sky-accessible, it will definitely amp up difficulty. Wouldn't recommend unless the melee attackers have some way to fly themselves, or the party can destroy his wings by aiming for them and beat him up when he falls. (Did that with a boss, worked pretty well, brought it down to range with the tradeoff of it being able to use it's own melee attacks effectively when it was downed.)
Like with the idea of Atikaya's mental faculties, the body would be capable of flight, but not in this fight -- it's a new ability to fly non-magically for a Rakshasa, and he like wouldn't be in a mental state to be able to figure it out the way he would if he executed the transformation in a more stable environment.


Thank you for the suggestions!