In the late game, when factions gain access to their nukes, the Eldar eldritch storm is massively underperforming. Enemy armies can stand in the storm, and suffer very few casualties, and the storm is currently a mostly psychological deterrent and something to throw extra elite points at.
As I see it, the main thing holding back the eldritch storm from being powerful is the lack of counterplay. Currently, if the storm did more damage, it would be very hard to stop it from wiping your army. Therefore, I would implement these changes
-Remove conduit form
-greatly increase the damage of eldritch storm, causing the damage to ramp up over time, and culminating in an explosion (like the storm in dow2)
-When the eldritch storm is summoned, an interactable "ritual site" is spawned nearby with several eldar warlocks channeling the storm, killing them or interrupting / knocking them down will cause the storm to completely dissipate
This would make the storm powerful, but would also give players the ability to react / cancel it