it has been announced in the next PBE phase that Xerath and the long-awaited Heimerdinger reworks will be coming.
?Xerath is plagued by having a high win rate but an incredibly low pick rate. This leads Riot to believe the champion just isn't fun and the time invested into him could be instead used on other, more reactive champions who pull similar records. Xerath is one of the higher skill-cap champions to play .
Heimerdinger, on the other hand, used to be one of the most powerful champions in the league. Constant changes to the game around him while he went unaddressed made him an unviable pick that would only bring a rise to the crowd as a troll mouseover in competitive play. This is due to the fact that his turrets are easily outranged and the champion has no innate escape abilities or tankiness, but is forced to push.
Posted by Xelnath on the official forums:
Coming in 3.13, 20thCenturyFaux will be gathering feedback and iterating on our favorite Revered Inventor - Heimerdinger.
When 3.13 comes to PBE, Heimerdinger and Xerath reworks will be available for testing, but not necessarily be shipping in 3.13. While we're not ready to release their kits today, I want you guys to give a warm PBE welcome to Faux. This is his first time taking heavy feedback on PBE, so please do your best to help him out!
Source - Riot Games