I think it would be interesting to see minigames get a buff from Krumblor if you have that particular building's aura slotted.
For instance, the Pantheon could have slot recharge times reduced 25%, Grimoire spells could only have 10% chance to backfire (or slightly faster mana recharge rate?), and farms could have slightly reduced seed planting costs or slightly increased plant effects. Triggering a Dragon Harvest buff could advance all plants 1 growth stage or guarantee seeds to drop if harvested during the buff.
The Heavenly upgrade could cost 2,525,252 HC.
Just some food for thought.