How viable is ice nova?

How viable is a tanky Ice Nova using Templar?

With the playstyle being running into packs and just spamming ice nova, with ice spear for bosses.

How about Hardcore?

low low low, when you get to a resist cold pack they own you

With cold pen support and buffed aoe and added elemental damage or faster casting it becomes less dangerous. Increasing the aoe range far enough so you can get archers makes it feel more effective. But anytime you are letting mobs come up and tickle you, it's gonna be dangerous.

I don't play hardcore but I have used frost nova on my totem for nearly the entire game. I now use a skeletotem but in certain situations I still prefer my frost totem. Elemental proliferation, faster casting and ice nova results in whole packs being constantly frozen. This worked really well for since I use a CI caster Templar whose main attack is spark.

I'm currently using it as my main attack. I toss out a few fire traps then run in and hit them with ice novas. It's pretty fun. I use glacial hammer with the traps for bosses. Currently level 35 at the end of act 3, but need some support gems to make it stronger.

ice nova and the trap support gem makes a fun cold grenade

its fun but like anything that goes into melee right now, its weaker than a ranged class.