Best spells for crit MoM Heiro build?

I'm currently running frost bolt/ice nova, and the damage is good enough (deathless a5 sirus was easy peasy), but the clear is mediocre despite huge AoE because the spell combo requires a significant amount of standing in place. Additionally when things get hectic it's really easy to miss casting a frost bolt which can end up with me either casting ice nova with no frost bolts (which is much lower dps) or casting ice nova on frost bolts that are already really far from me (frequently resulting in dying). I'm getting kinda tired of the gameplay being so clunky leading to enough deaths to have me stuck at level 93.

Here is the current build. https://pastebin.com/bsfD2kap

So what I would like a bit of collaboration on is this: is there a different spell that I could switch to with minimal gear/tree changes that would enable smoother game play? Is there a decent way to automate casting frost bolt with this tree? Should I swap to a staff cyclone CoC or something similar?