Maar, the Guilty Reaper is a figment of my imagination...for now.
Maar is a late-game mage-killer/duelist that relies upon his passive to make use of his late game potential. Most of his game play will come from using his two damaging abilities and ultimate in tandem in order to pursue and quickly kill targets before getting blasted away. Mana should be a factor in his build as all his abilities eat a fair amount of it and his own defensive ability actually scales with it. So yeah...