Legendary RE: Cataclysmic Converter
Cataclysmic Converter is intended as a form of support/dps style of Legendary RE. It regenerates mana for allies based on current health, deals damage based on current mana, and provides non-mana ability cost reductions (so it also benefits non-mana builds). It has extremely heavy mana costs, but pays off with high damage, and the capability to recover mana. Scaling Stamina boosts your support effects for casters around you via your health pool size, and scaling Intellect scales your damage output via your mana pool size and crit.
Your primary damage on this build is Invocation (Unleash), which scales it's damage off of your current mana, and consumes extreme amounts of mana for the ability. The less mana you have, the less damage you do, causing the damage to degrade with Invocation's use the longer it's cast.
Find your perfect middle ground of mana support for allies, or extreme damage.