via a solid source on Faeit 212
more details about the "Epic - The Horus Heresy" Starter Box;
The Box will come with enough Plastic sprues to represent 4 Legiones Astartes Battle Companies and Assets. This content can be use to build 4 small, 2 medium or 1 bigger Space Marine Army.
The Box comes with;
>36 Tactical Squads
>7 Assault Squads
>16 Heavy Weapon Squads
>7 Biker Squads
>8 Command Squads
>8 Terminator Squads
>16 Predator Tanks
>16 Vindicator Tanks
>12 Sicaran Tanks
>12 Land Raider Proteus
>8 Land Raider Spartan
>16 Contemptor Dreadnougts
>8 Leviathan Dreadnoughts
Rulebok, Istvaan III Campaign Booklet, Accessories ect.
Decals to represent all 18 Space Marine Legions
The Box features all four Legions of the Istvann III Atroscity with rules. There will be no "Legion A vs. Legion B fighting on Istvaan III" Theme for the Box and with the decals you could represent every Legion, but would need the Compendium to play other Legions than Sons of Horus, Empeors Children, World Eaters or Death Guard.
Apart from Plastic Sprues, there will be Resin Packs with Legion specific stuff like the Primarch, another Command Squad or Dreadnough Torso.