Codex supplement: Imperial Fists (HB) (8th Edition) (EN) contains:

The history of the Imperial Fists and their relentless determination to live up to the exacting standards of their Primarch, Rogal Dorn
A detailed description of Chapter organisation and iconography
An Imperial Fists bestiary with a detailed background for Captain Darnath Lysander of the 1st Company and Captain Tor Garadon of the 3rd Company
Key background information on the Crimson Fists – the legendary successor Chapter of the Imperial Fists – and a bestiary of Pedro Kantor, their valiant Chapter Master
A showcase of stunningly painted Citadel miniatures
Rules for Captain Lysander, Captain Garadon and Chapter Master Pedro Kantor
Stratagems, Warlord Traits, Tactical Objectives, Relics of the Fists and the Geokinesis discipline, defining the ways that the Imperial Fists wage war
And more!

You will need a copy of Codex: Space Marines and the Warhammer 40,000 rulebook to use the rules included in this codex supplement.

Codex supplement: Imperial Fists (HB) (8th Edition) (EN) contains:

The history of the Imperial Fists and their relentless determination to live up to the exacting standards of their Primarch, Rogal Dorn
A detailed description of Chapter organisation and iconography
An Imperial Fists bestiary with a detailed background for Captain Darnath Lysander of the 1st Company and Captain Tor Garadon of the 3rd Company
Key background information on the Crimson Fists – the legendary successor Chapter of the Imperial Fists – and a bestiary of Pedro Kantor, their valiant Chapter Master
A showcase of stunningly painted Citadel miniatures
Rules for Captain Lysander, Captain Garadon and Chapter Master Pedro Kantor
Stratagems, Warlord Traits, Tactical Objectives, Relics of the Fists and the Geokinesis discipline, defining the ways that the Imperial Fists wage war
And more!

You will need a copy of Codex: Space Marines and the Warhammer 40,000 rulebook to use the rules included in this codex supplement.