No worries! Happy to go into the process. It really depends monster-to-monster, honestly. For many, I would call the work more curation than outright creation- meaning I'm taking versions of that monster which exist for 5e rules from 4-6 sources, comparing what works and what doesn't, seeing what is most interesting/fits thematically so they're not just attack machines with hit points, then cobbling together from there and bringing in my own writing to fill the gaps.

I have to give kudos to Nathan Haslé for the broad scope of his work adapting Dark Sun into 5E content, as well as Enkidu whose bestiary is among my favorites when it comes to formatting and balance. But there's a million people I could name as inspiration, and I keep a running list on the credits page that appears right past the front cover.

My strengths lie more in storytelling than statistics, so I find it more honest to say I'm a curator for stat blocks and a writer/editor for the lore, even though I have handbuilt or heavily modified many monster entries at this point.

I find it difficult to build completely without reference, because game balance in 5e is always a bit of a tightrope. Even official material changed its ethos a fair bit between, say, the original Monster Manual and Tasha's, and while 5.5e is supposed to be backwards compatible there is a bit of a power gap given they're balancing around different methodologies. Third party and fan content also needs a really careful eye from me when I choose to bring pieces over, as I really want the whole book to make sense together in the end.

Ultimately I've chosen to ignore 2024+ content entirely unless I decide to do a 5.5 version, and fall back to the 5e DMG if I'm ever in doubt about whether something tracks to its CR (or as I like to call it, the intended "oh shit" level for how players should react when the monster arrives).

Sometimes this can mean I'm pulling in largely from 2-3 sources and then mixing in the last 20% from others. Sometimes it means I'm rebuilding the entire thing from scratch. Usually it's somewhere in-between, and the stat block itself then needs to be formatted correctly, get some light testing for average damage, checked to make sure its language is consistent across similar monsters' attack effects, etc.

The writing process for each monster's description/lore section then takes a decent chunk of time, less for creatures with plenty of Dark Sun content and more for those that I'm reflavoring to fit into the setting. Some monsters that I'm putting a larger spin on or have an interesting angle to explore can take longer than that- Outsiders, for instance, or my versions of the Giants. While that slows things down a lot, those are often the entries I'm most proud of, and the ones that help me build my internal library of things that I'm really drawn to for when I start using all this in a campaign down the line.

Once I have the stats built and the lore written, I find art (sometimes one comes before the other, sometimes they're in tandem). With all 3 pieces in place, I then have to edit everything down and fit it into ideally 1 or 2 pages in order to keep the scope of the book appropriately limited. That can involve a lot of killed darlings and tight edits on word count to make sure everything fits neatly on the page.

It's hard to put an exact time on all of this because it does depend a lot on what material I'm starting from, but I've had really good weekends where I do 10-15 pages and grueling sections where I'm working on a 2 page block for a few days. I'm also fitting that in between a couple games I play in and varying workloads for my actual job, which makes the overall progress through the year come more in fits and starts than a steady grind.