Thats because his skills have no cost! its utterly unbalanced, no cost, the longest cool down is 1 second. and there's no cast time! Atleast Nathanial has a sensible set of cast times and cool downs!
Edit; That was aimed at Gin, and Shiho don't worry, Natty's powers are actually balanced, have a look at cast times and cool downs, He's a very burst-y class, he relies on getting a fast kill. Also I've diliberatly left mana costs out since most of my mana cost's are percentile based.