PoB: https://pastebin.com/XKYGvvN2

No mirror tier gear required. My most expensive items are Divergent Ball Lightning, Awakened gems and Asenath's Gentle Touch gloves and the Bottle Faith.

A cheaper version of this build could replace the Asenath gloves with a rare gloves with mana, life and resist. You will be more tanky and have less stress on resist but the clear will not be as great. A double Crit multi jewel with mana goes for 2.5ex to 4ex depends on the amount of crit multi you get and you only needs 4 of them maximum. This build does scale on level however as the more points you invest on mana on tree, the more flat added lightning damage you get from the arch-mage support gem. Taking both Inquisitor and Pathfinder Ascendancy nodes means we have unlimited flask charges and ailment immunity on consecrated ground

The starting budget of this build would be somewhere around 15 to 20ex and could be scale to my version which is around 50 to 60ex. This is not a budget build to be fair but it is very reliable on the money spent.