Khawazu

Khawazu is refreshing to build because he causes multiple debuffs, yet does not really need Effectiveness. This allows him to build for pure muscle on his substats instead, focusing on Atk%, Crit Chance, and Crit Damage -- and Spd, of course.

You have an interesting choice when it comes to his primary gear set. A Speed set is the obvious choice, but another good option is Counter. Since Khawazu is pretty slow anyway and all of Golem's attacks are AOE, you might get more mileage out of Countering Golem's hits, especially if that means applying a few extra stacks of Burn along the way.

Because Khawazu's HP is high but his Def is low, it's very easy for him to activate Artifacts that trigger when the user's HP is low, and a lot of these Artifacts are very helpful for him.

• El's Fist is one of Khawazu's best options. As his HP falls, his Atk and Spd increase by up to 50%. This not only increases his turn-to-turn performance, but also strengthens his Burns, since they are based on Atk.
• If you don't have El's Fist, Sword of Morning is a good budget option that also boosts his survivability.

There are 5★ Artifacts that are good for Khawazu as well, but they are also narrower in their focus than El's Fist, which sometimes makes them less ideal.

• Durandal increases Khawazu's CR when he gets hit, but not his power. It's good if you run a Speed set instead of Counter. 
• Sigurd's Scythe, on the other hand, increases damage and offers lifesteal, but doesn't increase his speed, so it's better with Counter instead of Speed.
• Finally, Junkyard Dog is good if your team is focused entirely on Burn, as it essentially doubles Khawazu's chances of causing Burn without using Souls to do so.

Finally, make sure you use an Ego Fragment on Khawazu to switch his Devotion Aura to increasing his own Atk, which is almost always going to be more valuable for him and his Burn effects than the team HP aura.