Fire Hwa (Hwa)

Hwa (Fire Rakshasa) is one of the best attack monsters in Summoners War, she's a great single target attacker and can fulfill multiple roles at once: she is a continous damage dealer, a nuker and has attack bar and attack speed reducer capabilities.

Her skill setup makes her one of the best monster in Summoners war to use against Bosses: she can be used both in Giant B10 and Dragon B10 provided she has a good support team to help her surviving through the stages of the dungeon.

Hwa is very good also in Arena offence: her role here is to make significant damage while keep reducing speed and attack bar of a significant threat the enemy can have. This is better achieved if your team has also some speed and/or attack bar buffer like Bernard-Wind Griffon and Verdehile-Fire Vampire. 

Additionally with the introduction of Rift of Worlds, Hwa has gained a special spot in many team compositions of parties even for Raids level 5: she is most appreciated for attack bar and speed weakening effect on first skill and for that purpose she is often runed Revenge.

Since her first and second skill is Attack speed damage scaling, Swift runes are also a good option.

Fire Rakshasa in Giant B10

Hwa despite her elemental disadvantage is a good unit in Giant and that's for two main reason, while she prevent the giant from moving thanks to her passive skill, the rest of the floors every crystal enemy AI will target her and if runed with some HP she can survive and easily take down in one shot every monster in her way until the final floor. Keep in mind to use Veromos (Dark Ifrit) as leader and Belladeon (Light Inugami) to stabilize this team

Necropolis Dungeon

Here is where she can show her best (also in Raids as written below), she has multihit capabilities that can consume the Lich King's shield and she can apply Speed debuff.

In NB10 (and every other floor) attack bar manipulating skills doesn't work so don't espect her to take down 20% of lich king's bar but it is not so important because Hwa brings with her a skillset full of great tool to effectively defeat this boss, her continuos damage is another nice to have effect that can save you lot of time when combined with a good dps rune set.

Build her speed/crit damage and atk or hp (depending on substats) and try to reach at least +9k HP 75% Accuracy > 70% crit rate and a decent speed (+60 / +70 ). Speed here is not the key because is capped and you should try to make her go last in your team. If you are in mid-game feel free to use devilmon for her, you will find her useful even in PvE and PvP late-game.

A good team in Necropolis for mid-gamers that includes her could be: 
Veromos (L) -> cleanse + HP% leader skill
Colleen (Fire Harpu) -> Atk break , Heal block and multihit
Adrian (Fire Elven Ranger) -> multihit + continuous damage + dps 
Hwa (violent)
Fuco (Wind Lich) -> multihit + defense break + speed debuff + dps

Hwa in Raids 

Bad news here is that if you use hwa in NB10 you may need a different rune build for her to work in Rift of Worlds, first of all avoid violent runes because in this content they are more useful in cleansers and healers, speed here is a great advantage so you may need to reach +90 (swift runes probably needed) to make her viable for R5. Also you need more HP (preferred with substats), good stats here could be 19k HP, 190 speed, 70 Cr%, 50% resistance (you don't want her to be stunned and miss turns), +700 Attack and a good critical damage (>150%).

A good team for mid-game player (Raid 3-4 but will work perfectly even in R5 with some replacement) for her should focus the rest of the team on survival and obtainability so you could try:

- Xiong Fei (Fire Panda)
Obtainable from fusion, he brings 33% defense leader skill, he has a skillset ful of interesting debuff capabilities and is a perfect frontliner

- Dias (Dark Death Knight)
Passive damage reducing skill + unrecoverable effect and atk break (frontline)

- Hwa (backline)

- Lisa, Fire Neostone Agent (backline)
Cleanser + cooldown reducer 

- Chasun - Wind Sky Dancer (backline)
Healer and glancer

- Colleen (backline)
Healer + heal blocker and atk breaker

As you can see the only 5 star you need is fusionable, and dias was featured in a Hall of Heroes but if you don't have him he could be replaced by Darion (Light Vagabond) a farmable 3 star monster. Also if you are her but don't have hwa and you're looking for a great alternative you can take a look to Xiao Lin (Water Kung-fu Girl).

Hwa Suggested Runes

Mid/Late game: Swift/Focus or Swift/Revenge - SPD / %Crit Dmg / %ATK(or HP%)

Late Game: Violent (or swift or rage depending on purposes)/Revenge - SPD / %Crit Dmg / %ATK - 

Her passive can proc on revenge runes so consider them a really good choice in all contents