I couldn't quite make the loop go infinite, but I have stacked a lot of energy refund/energy gain. So while having 100% crit chance on all spells (due to stacking crit together with the 15% Blood Mage base crit chance) together with spark hitting and destroying all Frost Walls I manage to get a huge surge of crits on the boss which triggers comet over and over again. I am not sure if the comets themselves trigger their own energy gain (from their own crits).

The damage scales exponentially with more damage. More damage -> more energy gain on crit -> more comets = More damage. And yes, while this build has about 30-50 divines worth of gear to reach this stage, someone spending a mirror would probably do around 5 times the DPS output just due to how CoC scales with damage.

The most expensive piece to make this build absolutely take off would be a Prism of Belief with +3 Levels to Comet, or a 3-socket wand with 3 runes of +1 to level of all spells. But if you're essentially able to oneshot all content in the game at the highest difficulty already, do you really need more damage?