i tried to add every monster i find on editor to GM i will check again to make sure i ain't miss any. i also found trebuchets and siege rams that can be saved by GM. 
instructions:
-Add PAK file to  "Documents\Larian Studios\Divinity Original Sin 2\Mods"
-Click Cog icon in the game on GM Mode when selecting your campaign select "monsters...".
-Add the map "Monsters" as a Scene.
-Open the scene
-Right Click and Save the ones you want or all.
-Use "exported Characters" Tab in Creatures menu to use them on your own scenes. (for example look the pics)


Update 18/10/2017, 
-Added extra monsters like kraken and tentacles. 
-Added Diffrent sized models for many monsters (like dragons, trolls, etc.) and some big eggs for dragon eggs.
-Combined 2 map in 1 
-Added Some objects that can be saved and used.