The house's Knights' belch acidic vapours from their vents and exhaust ports, causing a pall of chemical smog wreathed them in battle. This smog is toxic enough, that it can dissolve the flesh and armour of anything that strayed within bounds of House Vrachul's Knights.
The Fallen Nobles of House Vrachul were known to favour the rush and crash of close combat with their Knights.
Due to pacts made with the Iron Warriors Warpsmith Etrogar, House Vrachul and the Chaos Knights of House Khomentis aided the Iron Warriors in their invasion of the Fortress World of Ghreddask in the Talledus System.
- Talledus War (Unknown Date.M42) - The conflict that raged upon Ghreddask was dominated by the presence of super-heavy war machines and enormous armoured battalions. Striding through the hailstorm of shells and rocket barrages came the towering forms of Imperial Knights, as well as their dark mirror, the dreaded Chaos Knights. Both of these bitter enemies upheld ancient oaths to their liege lords with unwavering certainty. In the case of the corrupted houses, their refusal to break the bonds of honour had found them fighting on the wrong side of the Horus Heresy, supporting the traitorous forces of the Warmaster Horus as they made war upon the Imperium of Man. House Mortan provided the majority of the Loyalist war engines on Ghreddask, with no less than six Knights hailing from the dark world of Kimdaria. Veteran beast-hunters all, the Mortan Knights hailed from a world wreathed in perpetual darkness and ravaged by predatory behemoths, a harsh place that had forged iron-hard souls. They proved invaluable in the battle against the Daemon Engines of the Iron Warriors Soul Harvester Scarax Krond, corralling the twisted abominations with fleet Armigers before tearing them apart with Reaper Chainswords and Thunderstrike Gauntlets. Both houses favoured the rush and crash of close combat, a craving that the Loyalist Nobles of House Mortan were only too glad to accommodate. Ghreddask shook to the impact of Titan-killing weaponry as these two ancient foes duelled, prepared to fight to the bitter end. Though the Imperial forces managed to blunt the Chaos assault, the fate of Ghreddask still hangs in the balance.
- Psychic Awkening - Faith & Fury (8th Edition), pg. 17