User blog comment:Emptylord/Season 3 - PBE Patch Notes/@comment-67.85.4.191-20121110014541/@comment-4922088-20121110020948

Haunting Guise is honestly useful for several champions with high base magic-damage that don't need the mana regen.

Vlad, Rumble, Kat, Kennen, and even Morde I've seen use this item to quite a bit of success.

The fact this item lacks anything to help champions with high base damage, but mana issues (ie Ziggs, Viktor, Fiddle) really is what makes it so rare.

It's an early-mid game power item, but why buy it on people who can use when it need mana so badly they'll never be able to cast spells and abuse it? They're better off buying other items to help them later on instead.