This setup is meant for difficult endgame content, such as Steel Path missions. If you are looking for something to use in normal missions and Sorties, check out my Speedgoth AoE Nuke build. This setup includes:

Sevagoth Build - Release The Kraken
Sevagoth's Shadow Build - The Kraken
Shadow Claws Build - Kraken's Klaws

The primary function of [Sevagoth] in this setup is to get into Shadow form as quickly as possible, giving us maximum uptime with the melee monster. We accomplish this by locking down all enemies in a large AoE with Ensnare (requires subsumed [Khora] via Helminth), priming them with Sow and Reap, and then killing them with additional casts of Reap or with an equipped weapon. As long as the enemies are still affected by Sow when they die, their souls will fill the well no matter what kills them.

Once the well is filled, we can jump into Shadow form and wreak havoc. Then you will just need to repeat the process whenever the well runs dry.