I could see the "natural world messing with you" feature split over two different grades in place of the invisibility one and that taking its place: perhaps an entangling effect [i know Freedom of Movement is a problem there, but it does hinder spellcasting and FoM is kind of broken anyway] for the first power and then some kind of full on damaging binding later on [the Complete Divine version of Briar Web should serve as a nasty basis]
In real lore, i've only really heard of invisibility while they're hiding after messing with you, laughter pouring out of nowhere, possibly why the Greater Invisibility doesn't seem very fairy-ish.
Those are just the thoughts of someone who's spent far too much time reading about/designing fairies.
As an aside, you mention the fire giants elemental link in your response on the giants thing [which may as well be called "Titan bloodline"] and i'm wondering if you have plans to add an elemental chain. It would certainly fit and Antimony from Gunnerkrieg Court could serve as inspiration.