Board Thread:Warhammer 40k General Discussion/@comment-24383134-20150518143519/@comment-6078851-20150519140635

the problem with any assault against commorragh is not just its scale, and the vast number of nasty critters therein, but its actual configuration.

codex quotes: "in the depths of the webway lies commorragh, the lair of the dark eldar, called the dark city by those who fear to speak its name. commorragh is no mere metropolis, for it is to the largest of imperial hives as a soaring mountain is to a mound of termites. its dimensions would be considered impossible if they could be read by conventional means."

"if anything, commorragh is more like a vast collection of satellite realms and cities linked by uncounted portals and hidden pathways. viewed from one perspective, commorragh is a loose collection of far-flung nodes spread throughout the arteries of the webway like a malevolent virus. its clustered concentrations are in reality scattered across the galaxy, thousands of light-years apart in some places. yet these locations are linked together by shimmering dimensional short-cuts. from within the webway's confines, the immense distances between each sub-realm can be crossed with a single step."

"... for the dark eldar are far more numerous than even their craftworld kin suspect. and not only is it the society of the dark eldar that festers within, commorragh plays host to many diverse species of alien mercenaries, bounty hunters, and renegades, all risking their souls in the hope of claiming the riches of the dark city."

to assault commorragh is to fight through the outlying satellite-realms, and every part of commorragh is very well defended by eldar technology, as well as dark eldar and any other species that lives there. raven guard are specifically infiltrators (although they probably got very lucky too) but exterminatus would only work on a single satellite realm at a time, and it wouldn't be long before the portals between sectors would start being closed.

another thing to remember is that dark eldar relish violence and death, even their own!, and things like the raven guard and salamander assaults only happen because the dark eldar allow space for it to happen - if they wished they could simply close all portals into commorragh. commorragh is assailable, but only because the dark eldar want people to attempt assaults so they can display their superiority, or experience some new violence :)

as i see it the only way commorragh will be threatened is from 1) a concentrated assault from hundreds of astartes chapters (at least hundreds), with very detailed knowledge of the inter-realm portals so they could travel straight to the heart of commorragh before the portals get closed - the most surgical of surgical strikes. 2) the potentiality of a daemonic incursion (which i think is the most likely out of these). 3) if a tyranid or two somehow get into the webway and gain a foothold in some small, unimportant satellite-realm that's largely ignored, breed prolifically (which is what they do), and then have a mini-hive fleet within the webway (that's somewhat unsettling). or 4) the dark eldar just get so bored with their lives that they open up every possible portal and start singing to the galaxy... "come and have a go if you think you are hard enough!" :P