Adam was the "first" man in the bible. Adamic means is an adjective meaning "related to Adam".
In the bible, Adam names all the animals in the world. Then "ecstasy" literally means "coming out of yourself", but it often means a trace-like state of extreme pleasure. An "ecstasy of naming" is a figurative expression meaning something like "such excessive naming of things that you enter a trance".
The idea here is that if you think that each narrative device needs a name, you will need to be like Adam and have to name thousands of narrative devices. (It is implied that you do not need to name every narrative device to have a useful discussion of novel theory)