Vishnu (July 2020)

Overview

Vishnu reps almost 25k HP, has 50% evasion, true light pierce for Thunderclap, and ice pierce [weak] for Ice Age. Vishnu also takes 50% less damage from his fire weakness.
Upon receiving the first killing blow, Vishnu heals 20k HP, so using demons with skills that nullifies death prevention skills, like Guts, Asura Lord, Susano-o A, and Skull Knight can make your way life easier.
Killing Kama would be a wise decision due to him healing everyone and applying Luster Candy every turn.

Encounter

Wave 1:

Ammut	Ippon-Datara

Wave 2:

Kama	Vishnu	Ose

Heal	DPS	Heal	Buff Control
Barong	Susano-o A	Lakshmi A	Vairocana
Samarecarm	Phys Amp	Samarecarm	Samarecarm
	Phys Boost

Seiran is the preferred Dx2 as she will provide random healing and increase healing effectiveness.
Lakshmi A is the cornerstone of this fight, setting up Five Elements while also providing heals and MP to the whole party. Kama is completely walled by Five Elements and will resort to auto-attacking.
Barong is actually a very strong healer now after the recent buffs. When combined with Lakshmi A, he can heal, setup full buffs and also restore MP to the team.
Susano-o A has strong piercing Physical DPS which also goes through Vishnu's Avatar, rendering the main gimmick of this Kiwami useless.
Vairocana purges off Kama's Fast Luster every turn, letting you easily survive.
Build up Boost levels for Susano-o A and Lakshmi A in the first wave. Five Elements will carry over if it is active when you clear the wave.
Samarecarm as insurance on everyone, since you only have one DPS unit.
Kill off Ose first; Kama will revive him so you need to kill him twice in total.
Leave Kama alive and go for Vishnu next. With Five Elements up, Kama will waste turns auto-attacking, resulting in Vishnu only getting a single attack per turn (which you can easily outheal).