You can add new monster manually on terrain files and create it's custom drop on World_Drops.scp =) good luck
can give sample how to setting on terrain and sample create custom drop on World_drop.scp ?????? .....
open scp and start check the script. it's not hard to create one .. you just need cords of the spawn and add them into the scp files.. that's not hard
for world_drop you can add whatever item you want to drop .. and require testing first and it will cost you a bit of time to make them work properly ..
Here you can orient yourself
https://youtu.be/IQLi7WyGPXc
https://youtu.be/9sFOic1rRAM