I think I will create something stat wise for the spawn - I have dragged out my old Call of Cthulhul RPG books and will work something out in that regards.
I will also add some house rules for the Nightgaunt to reflect CoC more.
My Mrs insisted the spawn wasn't "poisonous" or "toxic" enough as it was, and suggested I paint the suckers black with yellow in the middle. [which sounds very funny with her Japanese accent]
Being the sensible chap I am, I did what I was told....er what was suggested, and I am happy with the results... it does look more 'toxic'.
I will also add some house rules for the Nightgaunt to reflect CoC more.