May 2025 UK Goonhammer Open – Horus Heresy The Second Sphere Defence

Horus has come to Terra with a promise. The Throne World shall burn. The Emperor shall die. Humanity shall know a new master. With him he brings armies beyond counting. Raiders, reavers and daemons flock to his banner. 

But Lord Dorn, the Emperor’s Praetorian, has prepared the Sol System for this onslaught. Every available adult has been conscripted. Every bullet and shell scavenged. Every ship pressed into service. Entire systems fuel the war-machine needed to ensure this lynchpin of humanity stands firm against all that the Traitors can bring. 

But before the Traitors can break the walls of the Imperial Palace, they must first press through the fleet defences of the Sol System, and the valuable planets on its outer rim. The shipyards of the Jovian voidclans, the Saturnine space stations, Pluto’s seemingly impregnable ring of fortresses around the Kthonian gate, the mining planets of Neptune and the shipping lanes of Neptune’s Elysian Gate. 

Dorn knows this well, and has fortified the outer systems with all manner of defences. It is here we tell the story of the penultimate battle of the Heresy: THE SOLAR WAR.

An Imperial Fist Leviathan Dreadnought breaches the gates at the Goonhammer Open

Over the past few years, our Horus Heresy campaign events in the UK have been heading towards the endgame at the Siege of Terra. That time is nearly upon us. We’re pleased to announce that tickets to our biggest event of 2025 are now on sale – The Second Sphere Defence.

The Second Sphere Defence covers the opening salvos of the Solar War, in a campaign focusing on the moons, vessels and space stations surrounding the planets of Neptune and Uranus. Join us as we explore the untold stories of epic moments within the pivotal conflict over the weekend of May 10th/11th 2025.

Zone Mortalis at the Goonhammer Open. Photo Credit – Soggy

As always the latest event information and packs can be found on our event page here. If you weren’t able to make it to this one, save the date for our other events in 2025 which we announced here.

Come slam hams with us.