Witch
Blood Mage
Lightning Bolt from Choir of the Storm can generate energy for 
Cast on Critical setups. This build gets a bunch of spirit and then runs 3 separate Cast on Critical setups, featuring a mix of 
Arc and 
Spark for single target and clear, respectively.
It is okay to run one less Cast on Critical setup entirely. You can also opt to play at base 100 spirit with a single Cast on Critical and use a Focus offhand instead, but I like to feel many CoCs at the same time.
Blood Mage is mandatory for this particular build to firstly, sustain the cost of this many triggers and secondly, to provide enough base critical strike chance to crit cap for Lightning Bolt.
