3.5 was edition I played the most. It was a reason why I quit RPGs for nearly a decade because I hated it so much.
Every time I see another meme about how amazing 3.5 Tarrasque is, I remmember how amogn actual 3.5 players Tarrasque was the biggest joke. It was always brought up as definite proof designers have no idea how to make good monster. It was laughably easy to beat. A wizard could casually solo it, the same abilities people now miss in 3.5 amounted to ribbons. It was a laughingstock, forums had 100+ pages discussions how to fix it and general consensus was it';s beyond saving. It was first proof in 3.5 if you cannot use magic you're only good to roll over and die.
I honestly don't know if everyone claiming 3.5 Tarrasque is such a horrifying monster are trying to rewrite history or unintentionally proving what a broken, unplayable pile of garbage 3.5 was, if it's biggest punching bag is actually dangerous in a different, better designed game.
http://www.saltinwoundssetting.com/2015/04/salt-in-wounds-overview-origin.html?m=1
A campaign setting about a LE township whose economy is predicated on harvesting the perpetually regenerating form of the Tarrasque. The town is divided into districts based on the massive magical spears that have pinned the creature to the soil. And there's a ton of intrigue surrounding the various political families that are charged with maintaining - and periodically adjusting - those magical spears in order to keep the beast constrained, as well as the different religious, arcane, and druidic factions who have wildly different takes on if/how this process is to continue.
A very cool setpiece and one of the more exciting ways to describe how industrious adventurers might deal with this kind of creature.
I remember I Kickstarted this. The author realized he couldn't finish and just released everything he had done so far.
Edit: here it is https://drive.google.com/drive/folders/1kD7kYL-lOhwEW7-BLWU92B4WB2h1K6gH
Ah, thanks.