Skarner and Xerath have been nerfed! Increased CD and decreased range on Fracture for Skarner. Xerath has pretty much been completely reworked.
Don't get too upset, we all know this has to happen to balance out the game. Sure, there could have been a few others that might be at the top of our list (Heimerdinger IMO), but here's the list of patch 4.2 notes if you'd like to read up.