"Fire Fist", known as "Flame Star" (炎星Ensei) in the OCG is an archetype of FIREBeast-Warrior-Type monsters first introduced in the as Magazine Promotional Cards but from different magazines, and later expanded in Cosmo Blazer. In the OCG, every "Fire Fist" monster, except "Horse Prince", "Lion Emperor", and "Spirit", is named after the 108 heroes of Water Margin, the "108 Stars of Destiny"; the "Horse Prince", "Lion Emperor", and "Spirit" are characters from the novel, while the "Fire Formation" Spell/Trap Cards are named after celestials. Roughly a third of the heroes, the "Heavenly Spirits", have been released as of now.
As seen in the artworks, every "Fire Fist" monster has a flame which represents a monster/animal form, except "Spirit" who is a flame. Most "Fire Fist" monsters have a counterpart monster in the archetype with the same Level, ATK value and flame color. They can be seen together in the "Fire Formation" cards.
Currently only twenty-one "Heavenly Spirits" and three other characters have been released.
The first three "Fire Fist" monsters focus on Summoning Level 3 FIRE monsters, though they also have drawbacks. Their effects also indirectly support each other, making their respective Summons easier.
The monsters introduced in Cosmo Blazer have swarming effects initiated by sending "Fire Formation" Spell/Trap Cards to the Graveyard. But the support released in Lord of the Tachyon Galaxy have effects that initiate by sending not only "Fire Formation" Spell/Trap cards but "Fire Fist" monsters as well and their effects interact both the hand and graveyard. And the support released in Judgment of the Light have effects to Special Summon "Fire Fist" monsters from the deck and setting "Fire Formation" Spell cards when they are destroyed by battle ("Boar") or by card effects ("Caribou").
With the release of "Leopard", who sets a "Fire Formation" Spell/Trap by tributing himself or another "Fire Fist" monster, and "Rooster", whom when Special Summoned by the effect of a "Fire Fist" monster, adds another "Fire Fist" monster from your Deck to your hand, and also allows you to set another "Fire Formation" Spell/Trap by tributing one you already control, many players are adjusting their deck to run a more Synchro oriented "Fire Fist" deck.
This build of the deck focuses primarily on summoning the Synchro monster "Horse Prince" by using the Tuner, "Spirit" to resurrect "Leopard" or "Rooster", then get "Rooster's" effect to add another "Fire Fist" monster to your hand, and his effect to set another "Fire Formation" Spell/Trap from your deck (If you summoned him by via "Spirit"). Or, you can use "Fire Formation - Tensu" to Summon a "Raven" after Normal Summoning "Spirit", whom will let you set a "Fire Formation" Spell/Trap from your Deck when Synchro Summoned into "Horse Prince". But keep in mind, if you decide to set a Spell/Trap and summoned "Rooster" with "Horse Prince's" effect, "Rooster" will lose timing and you cannot search.
Another option is to summon "Leopard", then tribute it to set a "Fire Formation - Tensu". If you already have a "Spirit" in your hand, summon it, then resurrect "Leopard" and Synchro Summon "Horse Prince."
You can them use "Horse Prince's" effect to summon "Rooster" or even "Hawk", whom will boost all your "Fire Fist" monsters ATK by 500.
With the release of Fire Fists' second Tuner, "Boar", you can also add in your normal Level 4 Fire Fist monsters, "Bear", "Gorilla" and "Dragon", to keep control of your opponent's monsters, Spells/Traps and being able to Special Summon more "Fire Fist" monsters while also being able to Synchro Summon into Level 8s. Boar can Synchro Summon into either "Kirin", "Crimson Blader" or "Black Rose Dragon". "Kirin" allows you to Set another "Fire Formation" Spell/Trap card from your Deck when Synchro Summoned. Also, you can add "Coach Soldier Wolfbark" to set up plays like "Number 16: Shock Master" (Traditonal Format only).
Running the Level 4s and Level 3s also still gives you the option of Xyz summoning into "Lion Emperor", "Tiger King", and "Cardinal" if you choose.