Quick answer: At the Crimson Forest Sha-Chi Tower, speak to the Iron Fiend. Then visit the Iron Fist Master’s gravestone, roughly 39 m from the Burial Grounds bell. Use the two Fist Fragments at the grave to claim the Worldbreaker Fist.
How to start Heart of the Fist
Heart of the Fist is a tale in the Crimson Forest, and it begins with the Iron Fiend, Jade Dancer’s partner from Use It Against Them. He stands at the Crimson Forest Sha-Chi Tower, about 20 m from the Crimson Forest Sha-Chi Tower 6th Floor bell. If you still need that checkpoint, it is listed with the other bell locations.
Talk to him first. The gravestone does nothing until this conversation is done. Once it is, the quest log updates with this objective:
“Find the Iron Fist Master’s gravestone in the snow-covered Mirrorwood”
The map below marks the Iron Fiend at the tower.
Where is the Iron Fist Master’s gravestone
The grave lies in the Crimson Forest’s snow-covered Mirrorwood, at the same elevation as the Burial Grounds bell, about 39 m away.
Examine the gravestone to trigger a brief scene with incense burning; afterward, you receive Fist Fragment: Shell. The item card reads:
“A fist fragment left at the Iron Fist Sect Master’s final resting place. Its forbidding iron shell remains, but inside, it is completely hollow.”
Fist Fragment: Core
The Shell is only half the fist. The other half is Fist Fragment: Core, and its card reads:
“A fist fragment from the Iron Fiend’s gauntlets, still imbued with unwavering martial resolve. Those fists were raised only against formidable foes, to protect those worth protecting.”
“Collect all fragments to form the Worldbreaker Fist, used to Soul Temper the Iron Gauntlets.”
It is a reward from the Mu Xiaokui fight at the Lakeside in the Village of Lu, where the Iron Fiend fights at her side in the third phase.
Heart of the Fist reward: Worldbreaker Fist
With both the Shell and the Core in your inventory, go back to the Iron Fist Master’s gravestone and interact with it again. You receive the Worldbreaker Fist, and Heart of the Fist is complete. The card reads:
“Beneath the forbidding iron shell, what was once hollow is whole again.
The perseverance to hone one’s fists, the pursuit of greater heights in the martial arts, the resolve held within clenched hands, and the purpose behind every strike. Together, they form a fist powerful enough to shatter the world.”
Its listed use is “Used to Soul Temper the Iron Gauntlets.” That makes it one of the Soul Tempering materials, tied specifically to the Iron Gauntlets.
More tales are covered in the list of all side quests, and the rest of the area’s pickups are in the Crimson Forest collectibles.
