Yea seen that work too.
Kuthe is looking for un-traditional junglers and I really think Cass could pull it off tho mana dependant. Great aoe and single target damage plus a movement speed buff.
Her ganks would be fairly strong due to the damage and alot stronger with level 6.
Im personally gonna pick her up just to try it out, as for Karthus I own him but just don't enjoy his play style.