This build comes from Brozime's [Sevagoth] First Impressions video, available here. I've replaced [Fleeting Expertise] with [Rage], as not only does it save a Forma investment on the Madurai slot, but the lifesteal from Consume is extremely high and should allow for more risky plays on your health. [Stretch] has been replaced with [Augur Reach] for the set bonus, and Arcane Eruption also gives a greater level of CC around you.

This build requires 2 standard forma, to avoid the use of Umbral Forma.