Help me build: Gargantuan super-T-Rex!

[uraniumrooster]

I'm running a session for an on-going Eberron campaign. I'm not the regular DM, just doing a quick one-off, and I think a dinosaur hunt in Xen'drik could be fun. The party consists of 6 level 9 PCs: Bard/Cleric, Paladin/Assassin, Ranger, Sorcerer/Warlock, and two Wizards. They are a powerful group, well equipped with magic items, and were able to defeat a Demi-Lich (without lair actions) in two rounds without too much trouble (one of the Wizards got dropped to 0 by the Howl, but otherwise they were never too badly threatened).

Here's the inspiration for my idea: http://eberron.wikia.com/wiki/Lurking_Two-Maws

I'd like to shoot for about a CR 20, based on a T-Rex but bigger and badder, with some grappley battlefield control abilities and maybe a few extra surprises, legendary actions, etc. I'm going for a typical Deadly tier encounter... challenging, with the potential to result in a TPK, but ultimately winnable if the PCs use sound tactics (which they will, they're a smart group).

Your ideas are much appreciated!

[sxmedicus]

How about a lvl 20(or higher) Druid that somehow is able to use his Wild shape to turn into a T-rex... it kinda regenrates all his HP every turn but its not invincible at all.. just super annoying and spammy with spells and stuff, summoning all kinds of dinosaurs... I would join a campaign like that ASAP while gasping softly x)

[CoggieRagabash]

Given that it only needs to have a powerful theropod base, we've got a lot of room to work with. In no order, thoughts:

1. Making it highly mobile will go a long way to making it a threat to the whole group. You don't want your ranged to feel secure. Give it a high speed and powerful leaps.
2. While the t-rex base lends it some powerful single-target attacks, upgrading its tail attack to an AoE with a chance to knock-down or knock-back could help.
3. Its bellowing roar could probably be a painful field-wide attack with a chance to disrupt concentration.
4. Grappling with its jaws is an obvious choice built-in, but denies it the option to bite or roar. Giving it additional ways to grapple is ideal - either by giving it arms and claws worth speaking of (since we're not dealing with a t-rex exactly) or by adding on unnatural limbs like Lurking Two-Maws' tentacles.
5. If you're not married to it being a single high-power monster, having it have some minions could serve. Perhaps it has offspring in various states of maturation, every bit as bloodthirsty. This could provide a challenge if the group find cracks in the terrain to elude the big beast.

[Shining Wrath]

How cheesy do you want to be?


This dinosaur is ancient; it has survived thousands of years to get this big. Therefore, raise INT to 8, WIS to 20. This is a dinosaur that's "Seen it all". Play it accordingly.
As part of having high intelligence for a beast, it has learned to use its tail to hurl rocks and logs. Low accuracy (no proficiency bonus) but normal damage. Take away the usual "we fly overhead and rain death from above" tactic used for big dumb monsters.
It knows where to take shelter from storms, wild fires, dragons, and so on. It's got lairs it retreats to where any foe pursuing it has to fight it on its terms. It may even have a burrow speed for ad-hoc lairs.
It can jump high and far, and uses this ability for a special attack; a "pounce", if you will, where it makes an attack after moving in a straight line at least 30 feet and if that attack hits it follows with a full bite / claw / claw attack routine against the prone foe - it jumps on you from 20' away, knocks you down and then goes to town. And it's smart enough to do this to the guy in the back wearing robes and waving a stick, it learned to do that centuries ago.
Give it a devour feature - when it brings a target to zero HP with a bite attack, it swallows them. After 5 minutes, the body is digested and the dinosaur regains 20 hit points. And again, it's smart enough to break off combat and flee / hide in its lair until digestion is complete.
And anything this big that's a predator out on the plains has to be able to catch prey - ambushes just don't work so well when you're 25 feet tall and create impact tremors when you walk (cue Jeff Goldblum). It can run pretty fast but the key thing is it NEVER tires (for practical purposes).

[SharkForce]

don't forget the atomic breath :)

[HoodedHero007]

It could have 2 heads, and thereby could have 2 bite attacks, and perhaps (going off the previous post) have 16 INT, 8/head
perhaps take inspiration from the apparatus of kwalish for the grapples

[CoggieRagabash]

Possible deformities and mutations:


Give it extending jaws like a goblin shark and thus an unexpected reach attack that chains into a devouring ability like Shining Wrath suggested.
Its hide is covered in pustules that shed acidic or poison damage spray when sufficient damage of an appropriate type is dealt.
The creature's noxious maw is filled with a mysterious blend of bacteria and toxic compounds, afflicting those it bites with both a disease and a poison that rapidly wear down its health. Combine this with the hit-and-run strategies Shining Wrath proposes.
Its tail has split into multiple prehensile ends. This can allow it to act as a cat o' nine tails if swung slack, or grapple foes (multiple foes?) on a successful hit.

[uraniumrooster]

Awesome ideas, thanks everybody!

I'm gonna put together a stat-block this evening, stealing many of your suggestions. I'll post it here when I'm done.

[uraniumrooster]

I give you: the Old Tyrant.

Thought to be nothing more than a legend, told around campfires to scare greenhorn adventurers new to Xen'drik, The Old Tyrant is an ancient, two-headed T-Rex that stalks the jungles deep in the continent's interior. Her mutations have given her an unnatural lifespan, and she has learned from her experiences and developed an uncanny intelligence far beyond that of any beast. Her heads have fully independent personalities, but they are able to (mostly) cooperate and share one body effectively.

She is very territorial, and has staked out a large expanse of land that she considers hers. She will observe intruders from afar, gauging their strengths and weaknesses before choosing the opportune time to strike and drive them away. She has established several lairs spread throughout her territory, and will not hesitate to retreat to one of them and recuperate if she becomes badly injured.


Gargantuan Monstrosity (Mutated Tyrannosaurus Rex), unaligned

AC 20 (natural armor)
HP 300
Speed 40'

STR 28 (+9) | DEX 10 (+0) | CON 25 (+7) | INT 12/7 (+1/-2) | WIS 18/14 (+4/+2) | CHA 11/9 (+0/-1)

Saving Throws: Str +15, CON +13, Wis +10/+8, Cha +6/+5
Skills: Athletics +15, Perception +10/+8
Damage Resistances: Acid, Cold, Fire, Thunder; Bludgeoning, Piercing and Slashing from magical weapons.
Damage Immunities: Bludgeoning, Piercing and Slashing from non-magical weapons; Poison
Condition Immunities: Exhaustion, Frightened, Paralyzed, Poisoned
Senses: Darkvision 120', Passive Perception 20/18
Languages: –

Keen Smell. The Old Tyrant has advantage on Wisdom (Perception) checks that rely on smell.

Legendary Resistance (3/day)

Two Headed. The Old Tyrant has two fully independent heads sharing control of one body. Each head has separate mental ability scores and personalities, the larger head being older and more cunning, while the smaller head is younger and more impulsive. In combat, each head rolls a separate initiative and takes control of the body to act on its own turn. Spells and abilities that target the mind or the senses must target each head separately (anything that inflicts the Blinded, Charmed, Deafened, Stunned or Unconscious conditions). If either head rolls a 1 on an attack roll, ability check or saving throw, it blames the other head and must use its next available action to direct one bite attack at that head. If it already has another creature grappled in its mouth, it drops that creature to make the attack.

Running Leap. With a 30-foot running start, the Old Tyrant can long jump up to 40 feet.

ACTIONS

Multiattack. The Old Tyrant makes two attacks: one each with either her bite, tail or throw. She can't make both attacks against the same target.

Bite. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 35 (4d12 + 9) piercing damage. If the target is a Large or smaller creature, it is grappled (escape DC 19). Until this grapple ends, the target is restrained, and the Old Tyrant can't bite another target using this head.

Tail. Melee Weapon Attack: +15 to hit, reach 30 ft., one target. Hit: 32 (5d8 + 9) bludgeoning damage. If the target is a Large or smaller creature, the Old Tyrant can attempt to grapple it on a hit, making a Strength (Athletics) check opposed by the target's Strength (Athletics) or Dexterity (Acrobatics). The Old Tyrant can only grapple one creature at a time using her tail, but she can still make tail attacks while she has a creature grappled in this way. If she makes a tail attack while she has a creature grappled, both the target and the grappled creature take damage from the attack.

Throw. The Old Tyrant can use her tail to grab and hurl a boulder, tree, or creature she has grappled. She makes a Ranged Weapon Attack: +9 to hit, range 60/240 ft., one target. Hit: 35 (4d12 + 9) bludgeoning damage. If she hurls a creature she has grappled with her tail and hits, both the target and the creature being thrown take damage from the attack, and the grapple ends. If the attack misses, the creature being thrown takes falling damage appropriate for the distance of the throw, and the grapple ends.

Stomp. As a reaction, when targeted by a melee attack by a Large or smaller creature within 10 feet, The Old Tyrant can move above that creature (sharing their space) and attempt to stomp on them. The creature must succeed on a DC 19 Dexterity saving throw or take 35 (4d12 + 9) bludgeoning damage and be knocked prone and become restrained. The restrained condition ends as soon as the Old Tyrant moves, uses her Tail or Throw attack, uses her Tail Swipe legendary action, or takes any other action that would require her to lift her foot. On a successful save, the target dodges out of the way and is moved into the closest empty space.

LEGENDARY ACTIONS
The Old Tyrant can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Old Tyrant regains spent legendary actions at the start of her turn.

Roar. The Old Tyrant lets out a terrifying roar with one of her heads. Each creature within 120 feet that can hear must succeed on a DC 19 Constitution saving throw or be Stunned and Deafened for one round. Both of the Old Tyrant's heads are immune to this effect.

Tail Swipe (Costs 2 actions). The Old Tyrant swings her tail in a wide arc. Each creature in a 30-foot cone originating from the Old Tyrant must succeed on a DC 19 Dexterity saving throw or take 32 (5d8 + 9) bludgeoning damage and be knocked 30 feet away from the Old Tyrant. On a success, they fall prone and avoid both the damage and knockback. The Old Tyrant can choose to grapple one large or smaller creature of her choice that fails this saving throw, if she does not already have a creature grappled with her tail.

I haven't done the calculation. She's probably a bit over CR 20, but I think the group can handle it... or be smart enough to retreat. :smallbiggrin:

[JumboWheat01]

Aww... you already decided. I was gonna suggest something along this line.

http://monsterhunter.wikia.com/wiki/Deviljho

Gods, I hated when it showed up.

Still, your idea is pretty sweet. I might just show it to my DM buddy, see what he thinks about it.

[HoodedHero007]

If you want to lower the CR, remove some resistances, or make the rolling a 1 into just failing the check in general, and if you want to add in some comedy, give each head a different gender and put it in a clan of other regular T-Rexes, but the heads are on/off lovers and sometimes cheat on each other