The tarrasque is now a weakling [5e]

You know the tarrasque, right? D&Ds famous version of the Godzilla? Or something like that.

The legendary tarrasque, for there is fortunately only one known to exist, is the most dreaded monster native to the Prime Material plane.

The text is from the Monstrous Manual (2e). The one in the 5e MM is similar, although a bit less flavorful:

The legendary tarrasque is possibly the most dreaded monster of the Material Plane. It is widely believed that only one of these creatures exists, though no one can predict where and when it will strike.

The text is not the only thing that is weaker.

Of course, the tarrasque is still impressive in 5e. 676 HP, immunity to non-magical weapons, legendary resistance and legendary actions, challenge 30... But it pales in comparison to older editions.

I'll use 2e as an example because I like the Monstrous Manual, but it is basically the same as 1e. In 3e, the tarrasque is still VERY strong, maybe even more than 2e.

For example:

[2e] The mere sight of the tarrasque causes creatures with less than 3 levels or Hit Dice to be paralyzed with fright (no saving throw) until it is out of their vision. Creatures of 3 or more levels or Hit Dice flee in panic, although those of 7 or more levels or Hit Dice that manage to succeed with a saving throw vs. paralyzation are not affected (though they often still decide to run away).
[5e] Frightful Presence: Each creature of the tarrasque’s choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the tarrasque is within line of sight, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the tarrasque’s Frightful Presence for the next 24 hours.

As you can see, creatures with less than 7 HD had NO CHANCE against the tarrasque's MERE SIGHT... Now, 2 out of 10 peasants will be immune to its fear from 24 hours, and the rest will recover quickly...

[2e] a savage bite (5d10 points of damage plus acts as a sword of sharpness, severing a limb on a natural attack roll of 18 or better)
[5e] Swallow: The tarrasque makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite’s damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the tarrasque, and it takes 56 (16d6) acid damage at the start of each of the tarrasque’s turns. If the tarrasque takes 60 damage or more on a single turn from a creature inside it, the tarrasque must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the tarrasque. If the tarrasque dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.

Eh... 5e is good enough, but has lots of extra words and a bit less flavor.

Anyway, there are a few things that bother me about the 5e tarrasque... for example, it seems like a decent number of archers with +1 bows and the Sharpshooter feat could take down "possibly the most dreaded monster of the Material Plane". They just have to keep the distance.

I blame bounded accuracy...

But anyway, the thing I miss the most is this:

[2e] ... it regenerates lost hit points at a rate of 1 hit point per round... Slaying of the tarrasque is said to be possible only if the monster is reduced to -30 or fewer hit points and a wish is then used. Otherwise, even the slightest piece of the tarrasque can regenerate and restore the monster completely. Legend says that a great treasure can be extracted from the tarrasque’s carapace. The upper portion, treated with acid and then heated in a furnace, is thought to yield gems (10d10 diamonds of 1,000 gp base value each). The underbelly material, mixed with the creature’s blood and adamantite, is said to produce a metal that can be forged by master dwarven blacksmiths into 1d4 shields of +5 enchantment.

The tarrasque lost its regeneration in 4e.

Anyway, this spawned the concept of "The city built around the tarrasque", the best thing that came out of RPGNet as far as I can remember.

The concept has been expanded further in reddit, etc.:

https://www.reddit.com/r/DnD/comments/2rtwn3/the_city_built_around_the_tarrasque/

So basically you the a city built around an imprisoned tarrasque*, using its regenerating parts for all kinds of stuff.

(*Or, as I prefer it, the semi-dead, hallucinating carcass of the tarrasque).

Source.

So many good ideas spawned from this awesome concept.

Imagine the Tarrasque buried under a castle ... Maybe not everyone knows it is there, except some cultist, butchers... The city has small eathquakes from time to time, the nobles have discreet mutations, there are too many trolls in the area etc.

And PCs enter the picture without knowing what's going on. They may be invited to some of the nobility's peculiar banquets, where they serve the traditional meat dishes... Maybe they can take part in the invasion of this evil city (perhaps an expanding empire that has suddenly become too big to rule), unaware of the tarrasque's presence.

Picture the PCs discovering the monster AFTER they have defeated the city. How can they they maintain the shackles after the gaolers and butchers are gone?

Or maybe the other way around - the characters are hired to defend a city that will be attacked by bandits and savages (who, supposedly, covet the riches within).

[BTW, I wrote a one page adventure with a similar premise a while ago, maybe you can use it as inspiration].

In short, the saddest thing about the 5e tarrasque is not its diminished power, but the fact that it became a bit blander, and ignored one of the best monster stories created by D&D famdom.

As always... I really like 5e, but old school D&D is hard to beat.