User blog comment:Zerazx/Woe the Calamity of Mana/@comment-7481207-20140108103913

Mana drain is generally considered unfun in LOL, so a champion that does that really well would be "toxic". He also can only deal damage around every 14 seconds, leaving him useless the rest of the time (with the exception of his ulti, which I assume would have rather high cooldown due to how devestating it can be in teamfights). He will also most likely lose any lane against a manaless champion, such as Zed, Vladimir, Kennen and Akali.