At first, he wasn't able to control his power well. He would have lapses into "day dreams," which were dreams about killing his enemies, usually right before he was gonna do so. Shadora taught Seventy-Five how to control his power, in hopes that Seventy-Five would become less hostile to him and possibly assist him and Zeno in defeating Universia. Predictably, Seventy-Five didn't care at all (aside from wanting to know how he did it), and tried to attack Shadora again.
God Seventy-Five appears to have two special powers. He has a firey ring-like aura he has when he's transforming/first appears, and he can fire huge star-like energy balls. This form is truly the limit of Seventy-Five, according to Zeno, since he did not carry his 500% Omega form with him.