Try these, you can get very very detailed with them: https://smile.amazon.com/gp/product/B004SZ0YYU/
(That link shouldn't have any referral or affiliate nonsense added to it. If it does, that's Reddit's doing, not mine. I am not employed by, or affiliated with, Amazon or Staedtler)
Staedtler Lumocolor Correctable Pens are good fine-point pens that are designed to be harder to erase than regular dry/wet-erase pens (so once they've dried for a few minutes they won't smudge between sessions), but with a damp towel come right off.
My handwriting's horrible, but here's a laminated inventory/notes sheet from one of my characters that uses them (you can see around the brandy I smudged off some recent writing with my finger; using a wet towel would take that blue smudge right away): https://sumnerhayes.com/static/images/inventory.jpg
I picked up this set from Amazon.
​
​
Are these the 351 model? https://www.amazon.com/Staedtler-Lumocolor-Correctable-Pens-305FWP4/dp/B004SZ0YYU
I bought a laminating machine for about $20. You could always just stick the sheet in a plastic protecting sleeve, they're about ~$3 for a pack of 25.
These are the pens I use, they don't wipe off as easily as dry erase and they write a very fine line, good for details.
https://www.amazon.com/gp/product/B004SZ0YYU/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
You could always just print a bunch of copies of those sheets, especially if you have your encounters planned in advance. I just like to re-use my materials a lot so I don't have to refresh my gaming kit ever.
Sweet, I'll check 'em out. I found color for $10:
https://www.amazon.com/dp/B004SZ0YYU/ref=pd_luc_rh_bxgy_01_01_t_ttl_lh?_encoding=UTF8&psc=1