Help with BBEG D&D 3.5, all splats ok

[Dyrynify]

Ok, I am looking for help constructing an appropriate BBEG for my players.

Details:

It must be Colossal (a Tiny creature stepping out of the sea is... anticlimactic).
It, for plot reasons, must be extraplanar, but it's plane does not exist any more.
It is Evil, but the precise flavor is a toss up.
It is trapped here, but can get free of this plane if it eradicates all life on this plane. (Ancient binding spell that relies on the lifeforce of the living things on the Prime Material to power it.)
Build to challenge seven 18th-20th level PC's.
I influences the minds of mortals, encouraging worship as a god, and the sowing of chaos as a method of preparing for it's arrival.


Alright, I know, colossal evil extraplanar entity, trapped on this plane, looking to kill everything? Comes from the sea and mentally influences the weak willed to creat a cult? I am fully aware of all the cliches I am invoking. Please don't mention that. I just want help constructing a monster. As I mentioned, this is 3.5 D&D, and all splatbooks are fine.

[Juntao112]

Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ia! Ia! Cthulhu fhagn!

[Dyrynify]

Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Ia! Ia! Cthulhu fhagn!

Tha... that is not at all helpful.

[Juntao112]

There is a licensed D20 version of Call of Cthulhu (from back in 2002) that has Cthulhu statted up. Might be useful - iirc he is a Colossal Abomination from beyond time and space, trapped at the bottom of the ocean in the sunken city of R'lyeh and only able to communicate via telepathic dreams to his cult, which continually tries to free him. When the stars are right, he will rise and unleash a holocaust of flame and ecstasy upon the world as he frees himself and ascends to the stars above.

[Dyrynify]

That is much more helpful. Thank you.

[DMVerdandi]

Ok, I am looking for help constructing an appropriate BBEG for my players.

Details:

It must be Colossal (a Tiny creature stepping out of the sea is... anticlimactic).
It, for plot reasons, must be extraplanar, but it's plane does not exist any more.
It is Evil, but the precise flavor is a toss up.
It is trapped here, but can get free of this plane if it eradicates all life on this plane. (Ancient binding spell that relies on the lifeforce of the living things on the Prime Material to power it.)
Build to challenge seven 18th-20th level PC's.
I influences the minds of mortals, encouraging worship as a god, and the sowing of chaos as a method of preparing for it's arrival.


Alright, I know, colossal evil extraplanar entity, trapped on this plane, looking to kill everything? Comes from the sea and mentally influences the weak willed to creat a cult? I am fully aware of all the cliches I am invoking. Please don't mention that. I just want help constructing a monster. As I mentioned, this is 3.5 D&D, and all splatbooks are fine.

Hell, make the enemy a deity.
In the book they are built to challenge a 20th level party.


Chamoth the deep
Kraken
DR 10
Salient Divine abilities:

Alter Reality
Alter size
Alter self
Call Creatures (Kraken)
Divine water mastery
Increased Energy resistance (Fire,Electricty,Acid)
Power of nature
Know secrets

Only have the kraken starting collossal HD, 33.
Alter Reality should be FUN.


alternatively, make him a blue whale with dr

[GreenSerpent]

You could always modify an Advanced Aspect of the Leviathan from Elder Evils. Give it more Chaotic Surges per day, add the Extraplanar subtype, and refluff the Slam attacks to be tentacle attacks.

You might need to boost its INT and CHA scores though if you want it to be a bit more sneaky - it's less intelligent than the average commoner. But it is designed as a sort of ravening beast creature.

[ksbsnowowl]

It's only Gargantuan, not Colossal, but a Great Wyrm Black Dragon with the Half-Illithid template (the newer version from Underdark can be applied to more than just Humanoids).

The Great Wyrm Black Dragon is a CR 22, Half-Illithid is something like +3 CR. So, for CR 25, you get a big nasty monster that can fly, swim, breath water, and has SR 47.

It may be too high of a CR for what you want your PC's to face, but it's not uncommon for the 20th-level final campaign boss to be of a CR 4 or 5 higher than the party level. You also have a party of seven, so you're going to need a higher CR monster to truly scare them anyway.

[Asteron]

Ok, I am looking for help constructing an appropriate BBEG for my players.

Details:

It must be Colossal (a Tiny creature stepping out of the sea is... anticlimactic).
It, for plot reasons, must be extraplanar, but it's plane does not exist any more.
It is Evil, but the precise flavor is a toss up.
It is trapped here, but can get free of this plane if it eradicates all life on this plane. (Ancient binding spell that relies on the lifeforce of the living things on the Prime Material to power it.)
Build to challenge seven 18th-20th level PC's.
I influences the minds of mortals, encouraging worship as a god, and the sowing of chaos as a method of preparing for it's arrival.


Alright, I know, colossal evil extraplanar entity, trapped on this plane, looking to kill everything? Comes from the sea and mentally influences the weak willed to creat a cult? I am fully aware of all the cliches I am invoking. Please don't mention that. I just want help constructing a monster. As I mentioned, this is 3.5 D&D, and all splatbooks are fine.

I'll second Cthulhu. You pretty much described him to a T.

[Dyrynify]

Thanks, everyone. Lots of good options. I still have a while yet before I have to be ready for my players to find this thing, but this will help me build.