Fanaticism is extremely valuable to an Ice Nova build. 75% more cast speed is obviously very strong, and furthermore the 75% increased aoe means that enemies stay within the damaging region of Ice Nova for a longer period of time.

This build procs fanaticism by weaving in Frenzy and Shield Charge. Frostbolt is triggered by Spellslinger. As you can see from the video, this playstyle can be very responsive and quick if played properly. In this video, Fanaticism is active roughly 89% of the time.

The build also takes advantage of Inquisitor's new Righteous Providence node to go stat-stacking, low-life with Ivory Tower and easily gets 10,000 ES and 90% crit chance. The skeleton of this build would easily apply to all sorts of spellcasting inquisitor setups. It can also be done on a fairly low budget as you can see in the video.

Budget gear: https://pastebin.com/3w3vyT7S

Gear used in this video: https://pastebin.com/pDNrZpuu

Edit: Video of me clearing a t15 Canyon map: https://youtu.be/fGS2gbvjYJI