Tetragrammaton Under Siege

Tetragrammaton Under Siege is an ongoing campaign that is a part of the larger Indomitus Crusade, when the the Chapter homeworld of the Exalted Seraphs Chapter came under siege by a large horde of Fallen Angels and their Chaos allies. This massive battle is still ongoing, with no end in sight.

History
When the 4th and 6th companies arrived back at their Chapter homeworld, they find that Tetragrammaton has fallen under siege by an overwhelming horde of Fallen Angels. Slaangors and a Chaos Titan, led by a Fallen who had become a Chaos Lord devotee of Slaanesh, known as Shim'yaza. The Exalted Seraphs discovered that the Forces of Chaos intentions of their attack was to force the Chapter to fall to the Ruinous Powers, so that they would willingly join Luther's cause. These forces of Fallen claimed that they were the true loyalists, and that the Dark Angels on The Rock, were traitors.