Great googly moogly, its a Genius Loci! (Patreon)

It took me four false starts over five years, but I think I've finally figured out how to make a monster feel big well enough to do 3.5's genius loci justice. The core concept is you're fighting the whole landscape in multiple escalating phases, transitioning between combat and dangerous exploration as part of the process. It's flexible too; the Biome Cores lets you scale the difficulty or change the theming fairly easily.

Genius Loci

I've also got these Ciorcal Druids here from my friends over at Cobramode, which feel like a good fit if your genius loci needs heralds or magic-warped inhabitants:

Ciorcal Druids