D&D 5e: RWBY Nevermore

Miniboss at Galasen: a giant Nevermore
upload RWBY screenshots as pictures become necessary


Nevermore (giant bird thing), CR 24
Speed 30 ft, fly 120 ft.
600 hp
AC 22 (17 natural + Dex)

20 Str, 20 Dex, 24 Con, 13 Int, 15 Wis, 20 Cha

Saving throws: +12, +12, +7, +1, +9, +5

Damage resistances: fire, cold, lightning, force, physical from nonmagical weapons
Damage immunities: acid, poison, psychic
Condition immunities: charmed, frightened, poisoned

Dread emanation: all non-Grimm creatures who can see the Nevermore must make a DC 15 Wisdom save at the start of their turns. On a failed save, the creature takes 2d10 psychic damage. On a successful save, the creature becomes resistant to falling damage until the end of its next turn. (to encourage aerial combat)


Actions:

Ram. Melee weapon attack, area of effect 10 ft square. The Nevermore flies at a target and slams into it with its bone-covered head. Every creature within the targeted region must make a DC 20 Dexterity save. Each creature takes 6d8 bludgeoning damage on a failed save, or half as much on a successful save. This attack deals double damage to objects and structures.

Bite. Target must make a DC 20 Dex save. On a failed save, the target takes 2d10+5 piercing damage. The target is subject to the Held condition by the beak.

Talons. One or two targets must make a DC 20 Dex save. Targets must be within 10 ft of each other. On a failed save, each target takes 2d8+5 piercing damage and is Held by one of the talons.

Feather spears. Ranged weapon attack (150/450), +10 to hit, up to four targets who are not Held. On a hit, a target takes 2d10+5 piercing damage and is restrained until an action is taken to break or remove the feather.

Swallow. Special attack, usable only on a target Held in the beak. The target must make a DC 20 Dexterity save or be swallowed by the Nevermore. A swallowed creature takes 2d10 psychic damage immediately plus another 1d10 at the start of each of its turns. Additionally, a swallowed creature takes 1d4 bludgeoning damage for each 10 ft that the Nevermore flies while it is swallowed. A swallowed creature is blinded while they are inside. A creature may escape by dealing at least 40 damage to the Nevermore in a single round, or a total of 80. The AC for attacking from inside the Nevermore is 17, and it automatically fails Dex saves.

Drop. Bonus action, usable on any number of Held targets. The chosen targets are no longer subject to the Held condition, and they immediately begin to fall. A creature dropped from less than 600 feet up reaches the ground in one round. A creature dropped from between 600 and 1600 feet up reaches the ground in two rounds.


Held condition:
When a target is Held, it is restrained and is carried with the Nevermore as it moves. The Nevermore may not use another attack with the Holding part before either dropping the target (as a bonus action) or swallowing it in the case of the beak.


Mounting the Nevermore:
A player may mount the Nevermore as it swoops along the ground if they succeed on a DC 25 Acrobatics check or a DC 30 Athletics check. Each DC is lowered by 5 if the player uses at least 50 ft of rope to help them. The DC is lowered by an additional 5 if they have a friend assisting them.
A player Held by the Nevermore may attempt to escape its grasp without falling with a successful DC 20 Acrobatics check. They then must succeed on a DC 25 Athletics check to climb into its back from their current position.
The Nevermore may attempt to shake off a player who is riding it. The player must make two consecutive DC 20 Strength saves. A player falls if they fail either save.
A player falls if they ever fail to hold on with at least one hand.


Intro and strategy:

Begin with a Stealth roll from the Nevermore. If it rolls badly, its shadow passes over the party and they all get a free Perception check to spot it.
The Nevermore's first attack is a strafe low to the ground, attempting to Ram the whole group.
That pass should reveal to it who are the casters in the party. It will circle around and try to grab as many melee characters as it can, then fly out of range of the casters. If it grabbed anyone in its beak, it will try to swallow them.
It will drop any players held in its talons, or potentially try to throw them at the casters on the ground.
After dropping people, it will throw feather spears at anyone it can, especially the casters, before going in for another ground strafe or grab.





Falling damage:

Damage proportional to energy, which is proportional to velocity squared, which is proportional to height, assuming equal masses for everyone.
Terminal velocity is 176 ft per second, achieved after falling 484 ft. Round to 500 ft max height since we have above average mass due to equipment.

Can reduce speed of hitting the ground by equal amount as speed leaving the ground in a maximal high jump. Jump height is at most 3+[Str] feet.
Table: [Str] vs speed reduction vs safe height
0.    14 ft/s.
1.    16 ft/s.
2.    18 ft/s.
3.    20 ft/s.
4.    21 ft/s.
5.    23 ft/s.

Effective height = equivalent height without speed reduction as real height with speed reduction.

D ~ x = v^2/2a
X_eff = (v - v_safe)^2 /(2a)
     = ( sqrt(2ax) - v_safe )^2 /(2a)
     = ( 2ax + v_safe^2 - 2v_safe*sqrt(2ax) ) /(2a)
     = x + v_safe^2 /(2a) - v_safe/a * sqrt(2ax)

V_safe^2 = 2 a x_jump, so
X_eff = x + x_j - 1/a * sqrt( 2ax * 2ax_j )
     = x + x_j - 2*sqrt(x * x_j)
     = [ sqrt(x) - sqrt(x_j) ]^2

X is fixed, height fallen from
X_j depends on the player's Strength

Create table in excel:
Six columns, for each [Str] value
Height in units of 10 ft up to 500 ft max

Convert x_eff to damage in integer d12s. Highest value (no Str mod, terminal velocity) should do enough to instantly knock out but not kill a player. Maybe factor in that falling player should have the resistance to fall damage already? Then double max damage possible.