Battle of Othana V
The battle began when the haemonculi of the Twisted Spiral raised a vast bone fortress over the gaseous atmosphere of Othana V in the Vordrast System. However this world is extremely close to the Adeptus Custodes Star-Keep of Prescience, provoking a swift attack by the Emperor's guardians. Allarus Custodians of the Gilded Fist lead the attack, teleporting onto the nightmarish Osseous Tower. They overcome every fiend and abomination that assails them before destroying the tower's gravitic membranes and sending it tumbling down to be crushed in gas giant's high-pressure depths. The surviving Dark Eldar flee and vanish, but not before several Custodians go missing.