The Myths and Monsters pack is a Content Pack available in the mobile version of Little Alchemy 2.
Description from https://hints.littlealchemy2.com/content-pack/myths-and-monsters:
Discover fabled items, mythical gods and legendary monsters in the new Myths and Monsters content pack!
Use “immortality” to gather deities from a number of different mythologies. Bring fantastic creatures to life with the help of the “monster” item. And find the balance of the universe using “good” and “evil”!
Over a hundred new items from myths and legends from around the world are waiting for you!
Some more new "Fanon Elements" are available in the website, if you wanna know about them just type: "Folktales" in the search option, and click on the categories of it!
Currently, packs are only available on mobile devices and on Google Chromebooks through Google Play. But, you can wait to see if it's available.