new mobs for later.md

Note: Fix the beamos first.

Rules:

For now, Zelda + Dungeons and Dragons monsters. A few other things can come as well.

This project will be ported to 1.12.2 to see how adept I can be with modelling + mobs.

1. Tarrasque
2. Demogorgon
3. Xorn
4. Githyanki
5. Owlbear
6. Quickling
7. Rot Grub
8. Modron
9. Sphynx with all variants. Tameable and rideable.

Tweaks to do:

1. Let rust monsters attack modded metals
2. Modernize the codebase a bit